I can see the basics of an amazing game here, but the game seriously needs some work. Good thing they did the beta so these issues could be addressed.
1. Lag/slowdown. I was just in the GAF room (fun matches btw), and the game was hovering at around 20-25fps the entire time for me. Also, near the end, some of the hit detection was a bit odd.
2. Unbalanced health system. You can throw 1/2 a clip into a guy's body but it only takes 1 headshot to kill. Huh? Raise the damage done with a body shot and all will be well.
3. Stealth isn't that useful. This is a Metal Gear Solid game. The fights shouldn't all devolve into random shootouts like every other shooter. This one will be the hardest to fix.
4. CQC stuff is unbalanced and a bit unwieldy. The game doesn't do a good job of explaining what all the CQC moves are. Also, grabbing in CQC is a bit hit-or-miss, especially if there is a bit of lag. One more thing: the knife is way too powerful. Damned Gaffers and their exploits!
Two 400 MB patches should fix all of that, I reckon.