i've played the japanese one from the start and have been enjoying it. it's up to 5 story chapters so far, which i'm sufficiently interested in. plus there are bonus regions and timed events, so there is a lot of stuff to do in it. there is a bit of grind because it's an rpg and a mobile game, but there is also a 'full auto' battle mode which means you can just leave it sitting there while you do other stuff to grind for the easier battles.
being a mobile game that's free to play, you also have your standard premium currency (魔石 or magicite? maybe). you can buy this or get it from login bonuses or daily mission rewards or treasure chests in game for completing certain battles. but it is also an item drop (in quantities of 20 or more rarely 100) during normal battles too, so you can actually grind for that. it also doesn't do the 'two currencies' thing some mobile games do where you have a rare currency you get in game and another that is so rare you basically have to buy it and it's used for anything valuable
magicite is used for the following stuff:
- expanding the capacity of your card box [100 magicite for 5 spaces, 1000 for 50 spaces] or storage [100 for 10 spaces, 1000 for 100]
- card summoning if you do not have summoning tickets [500 magicite = 1 ticket, or 1000 for cactuar summon]
- most items in the item store [others being bought with gil with is a standard battle drop]
- continues/reviving yourself in battle if you don't have a pheonix down [100 magicite]
- maybe refilling stamina? i've never seen that since i've always had the items to do that but i'd guess that's going to be 100 magicite too
overall i'd say it strikes a nice balance for the premium currency. with something like record keeper, there's definitely parts where i think i'm being held back because i am not spending money on item draws to get better equipment (so i can't do the higher level dungeons beyond 100-120 difficulty which is where most of the items to build up your team higher like record dive fragments and rosetta stones are). but i haven't really felt like that with mobius, and if i have it was more down to feeling like i've not levelled up my cards enough rather than the game holding my not-paying against me. collecting the tickets and magicite to summon cards (the main way you're going to get stronger) doesn't feel as much as a drawn-out affair as gathering 50 mythril pieces in record keeper.
to briefly run down how the game plays since i keep mentioning bits of it, the basic layout is that you select a region from the world map, which takes you to another map where you select points on the map to enter battles and unlock new battles. once you complete the region you open up the next one, and there are usually a few side battles for you to do in each region. they also unlock a bonus region for each chapter, which has more treasure for you to collect. story scenes occasionally occur after battle (either fully animated and voiced scenes, voiced scenes with limited animation, and scenes with text dialogue and limited animation). you can replay the fully animated scenes from the 'theatre' section, and they also added a hard mode for each region that lets you replay each one in a new game+ fashion. you don't really get much chance to actually move the character around except in very occasional scenes where you can walk around a small area and talk to a few npcs for some text dialogue. but moving around is a little awkward so it's not a big complaint for me
for battles you select a job (you start with 3 base ones and summoning gets you a randomly selected job card), a weapon (unlocked by upgrading your jobs), and up to 4 ability cards (either dropped by enemies, or more powerful ones can be summoned). ability cards level up in battle, and can be upgraded/'class changed' by building them up to a specific level and using material cards dropped by enemies or received in other ways like login bonuses. the total level of all your cards determines your character level, and you can increase the cards' level cap by completing the story regions. jobs, weapons and ability cards have auto abilities which help you out in battle (strengthening attacks, extra gil/exp/skill seeds, other stuff).
in battle you either tap the screen to do a normal attack, or select an ability card to use. abilities require 'elements' which appear when you do normal attacks (or via abilities from weapons/cards). there's now 7 elements you can use in battle (fire, water, wind, earth, light, darkness, healing), either to activate an ability or to give you resistance to that element. using abilities (or via auto abilities normal attacks, or automatically each turn) fills up a limit break bar which lets you use a job specific attack. enemies have a 'break' gauge similar to the stagger (?) one from ffxiii, and when you break an enemy they don't attack and their defence is lowered. some enemies you have to break before you can do any proper damage, so that prevents it from just simply being a case of 'hit enemies with strong attacks all the time until they die'. breaking enemies and exploiting their weaknesses gets you a higher battle score, which in turn gives you more skill seeds (used to upgrade jobs) and is used for the weekly battle ranking which gives you rewards depending on where you place in the ranking.
they added a multiplayer area a while back where you fight large bosses (summons from past games) in a party of four, and recently added the ability to play on your own with an ai team and more recently the ability to give simple commands to them as well similar to what was done in some of the recent persona games. these bosses drop items which you can trade in for ability cards and exclusive weapons. they cycle the boss lineup so you if you don't get what you want you can just wait for the next chance. i haven't played this with other people, but the extra weapons look good. i do find the higher difficulty bosses too hard, though. don't know if that's me needing to improve my card sets or if it's easier with actual human parties.
they seem to repeat the limited time events they had in the past, so if you missed one of those there seems to be a good chance that you will get another opportunity to play it in the future.
graphics were one of the things they were pushing for this game, and it doesn't really look bad. i have an iphone 5s? i think (the one where they added a biometric home button), so i don't have the fancy graphical stuff they apparently made this to take advantage of. so sometimes i get slow down and screen tearing or textures looking a bit funny. plus some of the backgrounds look low quality. and there seems to be a lot of recycled models here. the general mook enemies are mainly palette swaps, and other enemies are just models from other games. the first boss from lightning returns is one of the first enemies you fight, and i think others have come from ffxiv (at least based on what i've seen from record keeper). they still look good quality, but it's slightly disappointing. the faces of the npcs also look like they were ripped straight from ffxiii/xiii-2/lightning returns, plus a lot of them just wear one of the main character's job outfits. it feels a bit like ffx-2 (where they wanted to see what they could do with resources they had already pre-made), but for a mobile game instead of a console this time. there are some nice looks bits, but there's definitely a lot of half-arsing going on too
i don't know if the english version will have english voices or japanese voices or a selection of both. i like most of the japanese cast for what it is worth (the v/a for 'voice' ������ good voice). there's also a few catchy music tracks, although i play a lot of the time without the sound on unless i'm playing a story/event area.
so overall, if i were to start ranking the square f2p mobile games i have played, i think i would put mobius up at the top (mobius > legends toki no suishou > record keeper > pictologica > g-bike). after a certain point record keeper started to feel like i was just playing it to collect new characters because the barrier to reach the higher level stuff just feels too high (it is currently running a beta test for 'nightmare dungeons' with a difficulty of 200 and like fuck am i going to try that when stuff just beyond 100 is too much) and there are so many characters that building them all up to be usable is a chore. pictologica is fine but it runs like shit and crashes constantly on my ipad so i'm bitter and lowered its rank. g-bike got to be grinding hell near the end of its life. toki no suishou is fine, though i haven't really put much time into that for a while now. it still gets support and updates and it's a generally fine game.
i just kind of like mobius better. it gets regular updates which add good features that make the game easier to play, there's regular events going on so even if you have completed all the current story there's still new stuff to do. it's got its faults but it feels more like an actual game than simply a time killing game like record keeper. so i'd say give it a go.