Caveat lector: I have not played any of the other Rainbow Six games, so I did not come into this title with many expectations. Also, I'm just jotting down thoughts in no particular order.
This was the first game I've played for more than a few hours on my Xbox 360. It felt easy to get into. Though the game had a lot of mechanics, they were introduced step-by-step, though I think I might have missed a few tips along the way. The controls seemed sensible for the most part, but switching weapons or attachments was a pain since both thumbs had to come off of the thumbsticks, usually with the left trigger held down.
The first person perspective was usually a hindrance, and I took cover just as often to see my character and what was around him as to avoid enemy fire. Since I couldn't easily track my squadmates or their status, I was regularly checking up on them visually, which can be annoying in a precise console shooter. I have to admit that I am not a fan of audio-only feedback on my squadmates. Tons of people are yelling, bullets are flying everywhere, and I often can't sort out what the hell is going on. The reality of war, but I don't want it on my Xbox 360, thx.
I liked that my squadmates would follow suit with me. When I crouched, they crouched. When I equipped my suppressor, they also equipped theirs. I'm not sure I understood how their stealth mechanics work, because I think I could set off a daisycutter in the room next to two guys and their response would be, "Did you hear something?" But it was nice to mark guys, open and clear, and hear the muffled bullets of my teammates as the dots disappeared.
Grenades felt more powerful/dangerous than in most games I've played, though the smoke grenades seemed to work inconsistently. Maybe that is by design. I thought that the weapons were not differentiated well. Perhaps they were trying to be realistic (again), but I felt little reason to select any given assault rifle over another assault rifle. Usually I wanted a weapon of a given class, with a certain attachment, and with the highest ammunition capacity. I carried around so many magazines of ammunition and came across so many equipment containers that only once in the game did I have to pick up the weapon of a fallen enemy.
The level design was very interesting, as I usually had several options for traversing any environment and engaging any given set of enemies. I was always looking to the left and right, up and down. Very good use of vertical space. And despite the fact that I was fighting humans with guns throughout the entire story, I never tired of it due to the different environments and challenges that they presented.
"Hold this spot while Jung **** around on a computer out in the open" moments were among the most irritating in the game, a sentiment two of my co-workers agreed with. My annoyance grew when I realized that the computers were always placed facing in (toward a cubbyhole) to prevent you from taking up a tactically sound position when the inevitable clown car full of guys poured forth. Those sections seemed to be very "against" your game training. "Guys, sit in a box facing outward toward a field full of potential murder camps."
My squadmates usually moved very well, and I was impressed by how smart they were -- both with and without orders. However, on a few occasions they would try to move to the inside of a door when I would command them to move to a doorway while looking through my snake cam, when in almost all cases the desired effect would be the opposite.
Rappelling was a lot of fun, especially when I could set up my squad to breach just as I came in through a doorway. There were some really fantastic firefights following that sort of set-up. I also liked the use of thermal goggles and how they would often be foiled by flames, generators, etc.
I thought the story was fine, but the terrorist characters were pretty absurd. Irena just seemed like a dumb, generic terrorist and I didn't really care about killing her. Her motivations were unclear, and I didn't have any real attachment to my early Rainbow team members, so I never got as pumped up about tracking her down as my character was.
Despite its few gameplay flaws (and the fact that sometimes levels will load without textures), I thought this was a very fun game overall. I felt like my shooting skills and my command skills were equally important. My teammates were valuable, I was valuable, and it seemed as much about tactics as taking precise shots at the bad guys. I award this game 6.3 of 8 flashbangs.