I've only played one round of Customs so far (obviously the amount of people trying to play is making things hard) but already the game just *feels* so much better!
The intermittent frame stuttering that happened in 0.11 when players would come on screen or you would aim down sights seems completely gone, the performance just feels so much smoother than before, even the way the character moves feels like it's somehow more natural and smooth.
I love the new prone movement sounds! And that long range foliage! WOW, it's so good to finally feel like lying in long grass may actually be hiding me. Having the foliage out to long distances just makes the whole world look so much more complete despite my computer not being able to run very good graphics settings.
The engine migration seems like it's really been worth it already with just how much cleaner the actual shooting and moving part of the game feels now.
TLDR: Great work BSG! Keep it up, one round in and I'm already really enjoying 0.12!