First and completely foremost is the reduced input delay. It's absolutely amazing. Suddenly the game feels so smooth and responsive, it's unreal. All the improvements to squad behavior are completely spot on. Cover works more intuitively. The 'core' of the game is just so much tighter it's like heaven. No longer does some random guy stand out of cover. No longer does your whole squad do a weird dance before firing their weapon at the target. It's like I used to be playing blindfolded and now I can see.
Second is the bugfixes. Oh god the glorious bugfixes. Machine guns moving and setting up properly, WORKING IN BUILDINGS, retreating without stopping, abilities working how they're supposed to, it's practically too many to list (which is why we have the bug tracker
![:D :D](/images/Smileys/biggrin.gif)
Third are the balance changes. I personally agree whole-heartedly with all of them, but I won't comment overly on them since I'm sure they'll all get their own threads in due time where they can be "discussed" further.
Also buildings seem more intuitive now. Stukas won't one shot them and they seem a little sturdier in general.
Above all, download and play for yourself and share your thoughts! The more people participate in this beta, the better it will be on launch day (next week?)