The main thing (and referred to indirectly in the title) is that they overhauled the Exploration job / activity, streamlined it, made it more accessible, and gave it more depth. Scanning is less tedious (all drones are launched at once) and easier to use (pre-set formations, all drones can be moved at once in that formation instead of manual), and the UI for scanning is a bit more obvious - scan strength is shown as a progress bar of sorts, and iirc you're able to see history and probably move your drones back to where they were.
Also, whenever you enter a system or exit a station, a scanner sweep is done automatically, to point out weak signatures (exploration sites) and the anomalies that get instantly 100% (pve combat sites, pirate / drone hubs and the like).
Exploration site running has been enhanced, some tweaks / changes made to looting, and they added a minigame to both hacking and that other thing (archaeology / scanning?).
Further improvements include an attempt to improve immersiveness; they changed something to the music and what plays when / where, and they've reduced 'sudden' changes and loading bars when undocking (animated undock icon), using jump gates (fancy ZOOM YOU GET BLOW THROUGH IT YAAAAY animation), when about to die (better visual clues your shields / armor / hull is down), when dying ('pod ejecting' animation of sorts), and when
really dying (zooms in on your frozen corpse and gives you a visual hint your clone is being activated, instead of suddenly dumping you back in a station which usually makes anyone go WTF WHAT HAPPENED when getting smartbomb'd).
Another new trade / money-making / criminal opportunity is that you can get special items from special NPC's / pirates, which can be used to increase your security status - or be sold / traded on the market. This'll probably eventually cause more highsec crimes happening though. And moar money made by some,
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Finally, new ships and whatnot (or, new variations of existing ships), some rebalancing, and a ship skill rebalancing / rework; battlecruisers and destroyers (and maybe battleships? I don't recall) now all have a racial variant, and flying a class of ship now has more prerequisites to avoid or flatten out people training up to fly big ships without actually being able to do anything with it (this is me, lulz). People that trained racial frigates to 3 and Battlecruisers to V got a shitton of free skill points (we're talking 7.5 million SP here, which is like 5-6 months worth of SP), because CCP isn't taking the ability to fly a certain ship from existing players. I decided not to train up for that, would've occupied my training for like two months and I wasn't sure I'd still be playing by then. Eh. I'm still not crosstraining into other races, so fine by me.
I should glance at it for a bit before heading off.