Rainbow Six 3 is a great tactical FPS with realistic and entertaining gameplay.
One of the best things about this game is the team commanding ability. In other games, you can command people, but usually they just run off and do their own thing. However, in this game, the commands are precise, and your men do exactly what you tell them to do. If you want them to open a door they do it. If you want them to hold position, they will do so until you tell them to follow. This works well with the game because you cannot have stealth without accurate team command.
Another thing I was impressed with in this game was the AI. Unlike other games, enemies don't just jump out at you and start firing a shower of bullets. They will throw smoke grenades, cocktails, and flash greandes to try to slow you down first. Then they will usually hide behind a corner or something like a table or bench, and then they will fire at you. I liked this because it made the game a bit more challenging than traditional FPS games.
The graphics in this game are also pretty well done. Although some of the environments look undetailed at times, the guns and the characters look great. All of the firing and explosions are realistic, and I especially liked how your played reacted to the flash grenade. Its almost like when you look at the flash, it takes a picutre of what you see when the flash came, and that picture stays in you vision almost transparently no matter where you look. I just thought that was a good idea.
Although some of the missions are a little repetitive in this game, there is a lot of good that comes from this game. Like I said before, if you liked the other Rainbow Six games, or just like Ubisoft games in general, then you will most likely enjoy playing this game. It is entertaining, and it has a pretty fun multiplayer mode that will keep you busy for a long time.