I absolutely love the new nebulae (or nebulas?) and the sense of direction in space they provide. Same with the stargates: they now actually point in the direction you're supposed to travel! For a game environment, it all looks and feels surprisingly real. This snapshot for instance shows a regular piece of space, nothing fancy, but it really looks like a picture of our own milky way at night. I didn't think changing the nebulae could enhance the level of immersion, but it does for me.
Other 'Flying in Space' features I am quickly getting used to: right click on a remote stargate in overview and select 'jump'; warps you to the gate and jumps you through. Very neat. Same with selecting a station from your asset list and select 'destination': autopilot will now bring you to that station and dock you. Again - very useful. The 'loot all' button is a boon when ratting or missioning, less mouse clicks!
Another feature that makes me happy: if your ship does an emergency warp (usually caused by an unintended disconnect from Eve: network failure, power failure, PC crash..) then your drones will attempt to return to the drone bay before your ship warps off. I've lost quite a few drones due to emergency warps, hopefully this will help! Plus, when you forget your drones out there (and who hasn't) the Crucible client will let you reconnect to them once you return to the area you left them in, so they don't get lost that easy.
I realise I'm supposed to sing the praises of the new battlecruisers, but the truth is I haven't had a chance to look at them properly, let alone buy or fly one. And as soon as I get my rusty Dominix out in space for a level 4 mission, I may be able to judge the positive effects of the buff to hybrid turrets; so far no experiences there either. And a myriad of other small fixes I haven't testedyet..
So far, I like Crucible; kudos to CCP for getting this out of the door.