At first I was a bit apprehensive about spending £60 on a wired mouse that looks like the only advantage to using it would be for playing MMOs (specifically, World of Warcraft), but where this might have been the case when the mouse first launched, it no longer suffers from that limitation today. With the latest software you can configure and assign every one of the 17 buttons to your hearts content, and it's even smart enough to automatically switch profiles on the fly as it detects which program you're using. For my purposes this not only includes a variety of games, but when I need to get down to work I can happily use shortcuts on many of my other apps such as Photoshop and Maya - it makes switching tools and quick saving a lot more accessible and comfortable. For more specific or complex commands you can create macros which will record all your keystrokes, and then assign them to a single click, it's absolutely perfect. Furthermore, there is a switch on the bottom of the mouse that lets you switch the number pad 'profile', allowing you to use another set of 12 configurations on top of the 17 if you ever feel the need to do so (think of it like switching a profile within a profile) - it's excessive and hardly anyone will use it, but hey, it's an option if you want it.
In terms of ergonomics, I did have to get used to it at first - but that's because I came from using a wireless Logitech, which has a huge curve on the left side to rest my thumb. The Razer Naga does not have this, but does have a curvy recess on the right side for the ring finger to sit on. It is now very comfortable to use, and the surface has a very soft, smooth feel to it. I did not have any problem getting used to the number pad either; they buttons may look small, but are easy to find and press even without looking. It does come with rubber stickers for those who need a more tactile form of guidance while getting used to it.
The only complaint I have is that the back/forward buttons are situated right next to the left mouse click, which is very awkward to use, but is only really placed there because of the abundant amount of keys on the number pad. In this case I'd recommend ignoring those buttons and just assigning your typical back/forward to any of the keys where your thumb rests. Other than that, I'd highly recommend this mouse. It not only looks great, feels great, but is very responsive with a DPI of up to 5600 (which can be adjusted on the fly). Get one now, you wont regret it.