Just game wise the 2.1 is quite a bit more stable than 2.0 I managed to fly with a friend for couple of hours and CTD happened around 3h mark.
Still random bugs like ship repairing sometimes killing you, occasional ejections.
No slowdowns anymore due to AI pirate spawning (or whatever the issue was before).
I did my share of hopping onto other player ships to copilot, turret them, but nothing much to do there atm.
Turrets are still pretty unusable. While pilot can see pirates easily on overview in turrets you just see green targets. on some ships you can cycle and see in status window who you are targeting. in some ships it does not work.
Super Hornet turret is still super slow to turn, so completely unusable.
Doing the Covalex "glowing pad hunt" mission together shows the other guy twitching around in EVA mode.
Arena Commander supposedly took a dive for the worst with people crashing quite often.
So in summary: PU is better, but nothing to get much invested in yet. probably will take another few hour look when 2.2 hits live.