Razer Naga is great for MMO's but only if you utilise the multi button thumb pad if your not a fan of having all those extra ones on the side you would not like that mouse. Ofcourse if you currently use a gaming keyboard with a lot of macro keys on it then you can switch some of these to the naga mouse and spread the work over 2 hands or the downside is in moments of pure frustration or something hit the wrong button on ur mouse and make mistakes ;p
The naga is also meant to be pretty handy in FPS by assigning the buttons to weapon switching ect but that is not something I have tried.