Lost a fair few hours to Ghost Recon Online so far this week. My thoughts so far:
A lot more tactical than GRAW. The team that communicates the most, calling out targets, talking strategy etc will win every time. Walking out into the open for more than a few seconds gets you killed. So that's a plus for me. There's also plenty of reasons to stick close to your squad, i.e health and ammo topups and device recharges.
The device functions are interesting, but not too overpowered. The time that it takes for it to recharge makes it a tactical weapon and not something that you can use all the time.
Gameplay is fairly smooth and not buggy at all, only turning on vsync nearly halves my frame rate.
The real downsides are obvious: no dedicated servers (as far as i can tell). It's all matchmaking, and for some reason every time a round finishes the game finds me a new match, which is frustrating, especially if i'm having a good game with a good team.
The price is right however, i'd definitely recommend it...