Excellent build quality, the material and construction of the mouse is sturdy and yet stylish. The Naga is smaller than other gaming mice I've used over the years, but by far one of the most ergonomic and comfortable of them all. The accuracy and flow of the mouse is unparalleled, especially evident when using a Razer gaming mat alongside it. Even the cord, a seemingly unimportant aspect of the design, has been given a makeover, with a fibre casing that speaks of quality.
And that's just the mouse on it's own. The thumb operated keypad fulfils it's role beautifully. As a heavy MMO, RTS and FPS player, this handy addition has enriched my gaming experience through the freedom it provides my keyboard hand with. The buttons are easy to depress, unobtrusive and the time it takes to get used to the operation of the buttons wasn't very long either.
In World of Warcraft this mouse really shines. With an excellent UI addon available from the Razer website, you can assign skills to the number pad on the side. Not to mention the extra two buttons on the left of the primary click, which are handy as mount/demount and call pet buttons : )
Although this mouse isn't purely exclusive to MMO gaming in it's use - in FPS games you can map weapons to the keys, in RTS titles you can control unit groups and buildings at the touch of your thumb.. in any game, there's a way to use the Naga to your advantage.
The only downside of the mouse is possibly the size (which is quite small). Some seasoned gamers will find the transition to the numpad a little daunting at first, and there aren't custom additional weights for the mouse.
Overall, top buy. I'm 100% satisfied and have already convinced most of my friends to buy one!