I played NS1 religiously for years and at a competitive level, so my impressions are admittedly tainted by that. Had I known what NS2 would look like, I wouldn't have shelled out the $40. I know I seem very dissatisfied, but it's only because I had very high expectations - if you're a more casual player, chances are you'll be pretty happy. I'll try not to touch upon game balance since that'll change in the future and stick to gameplay fundamentals. With that in mind:
Performance still needs improvement. My 2500k @ 4.3 Ghz still struggles to maintain a smooth and responsive framerate. During the Alpha fanboys were saying performance would be fixed by the Beta and during the Beta they were saying it would be fixed by release. They actually did put out a patch right before public release that significantly improved performance, but I still consider it deficient. Maybe they'll work another miracle in the future, we'll see. The engine was literally written by a single person, so I'll give them some slack.
Ammo and energy levels are small and hard to see. If you try to connect to a server but fail, you have to open up the server browser and wait for it to reload everything all over again. Even worse, refreshing servers can overload my router and disconnect me. I wish the developers should pay more attention to these things because they're niggling problems that are all easy to fix but when taken together really eat into the experience.
Skulk movement needs improvement. Hell, all movement needs improvement. Everything feels like it's moving in molasses. Personally, I thought wall hopping and bunny hopping in NS1 was perfect, but UWE decided it was too unintuitive. Instead, they've come up with this new wall hopping mechanic where you jump off walls at a certain angle to gain speed and keep mashing space bar as you hit the ground to maintain it. It's not obvious to me this is any more intuitive than what it was supposed to replace. At the same time, they've given Marines sprint (Which some players have unhappily pointed out is just slightly slower than a running Skulk) but completely nerfed their ability to move backwards and dodge by jumping.
Sound is muffled. Everything sounds like a heavily carpeted room and it's hard to tell what direction a sound is coming from or even what it's supposed to be. For a game so dependent on flanking and ambushing, this is pretty big.
Not too happy about the power grid/infestation mechanism. I guess Flayra added it in to solidify the concept of map control, but it comes at the detriment of a more dynamic game. Now pushing through Alien territory is always a slog - no more quick surprise rushes or ninja phase gates.
Don't like the Alien commander. There used to be a clear difference between Marines and Aliens - Marines had a top-down structure where a single commander dropped equipment and buildings while Aliens had a decentralized one where individuals would go Gorge and build whatever they wanted. Now the defining difference between the two teams is ranged vs melee, especially now that Marines get personal resources instead of having to rely on the commander spending the team resource pool. I'm not sure why this was added in at all, Flayra seems to get these ideas in his head that don't really have backing behind it other than "Hey, this seems like a cool thing to do!"
Lots of visual clutter. I can't even keep track of the number of things Aliens can do that obfuscate your view, never mind the various visual effects from other sources.
Cyke: I got a Steam friend in Malaysia who plays, so I assume there are at least some servers available in Asia.