If your a fan of the series chech it out !
Multiplayer was enjoyable in a sense that teamwork and accuracy were the most important factors which made sticking together a necessity. Online capabilities is what made this game even a thought to buy. I enjoyed it alot since I like FPS and teamwork. Headshots are mandatory online but lag wasn't an issue. When you get killed, they put in this "Spectator Mode" through which you can watch the gameplay from the camera of a another person (1st Person or 3rd Person).
All in all Rainbow Six 3 was enjoyable to say this least. Multiplayer is what kept it going and gameplay is what is keeping it here.