UPDATE, 4/18/2009: After nearly two years, my DeathAdder has been experiencing problems. The finish is starting to come off of the top of the mouse, and the left mouse button is intermittently cutting in and out such that if I try to click and drag anything, it stops halfway through. Thankfully, the warranty is two years and I will most likely be getting a replacement. However, before you read the glowing review below, keep in mind that you may suffer issues in the long term.
I'm a gamer, but loathe PC-based first-person shooters. So one might think this mouse overkill for someone like me. However, I splurged on this mouse anyhow thinking it might come in handy elsewhere, be it in Warcraft 3 or just a web browser.
The first thing you notice right after you plug it in is that it looks cool. The scroll wheel is a bright blue, and the Razer logo gives off a soft blue pulsing glow. However, you can turn the lights off in software if this isn't your thing, which is a nice plus...
...once you can get the software to work. I'm not an inexperienced computer user by any means, but simply following the directions included in the package resulted in the mouse software claiming that the DeathAdder was not connected when it clearly was. All I had to do was go to the Razer website, download driver version 1.05, uninstall version 1.03 (which required a reboot), install 1.05 (another reboot), and it worked just fine. It was merely annoying, but certainly worth noting.
With that out of the way I've found the mouse extremely comfortable (though unfortunately it's ever-so-slightly curved to one side, which means southpaws need not apply) and very, VERY responsive. It never skips, jumps, or glitches. The buttons are easy to click but not so easy as to cause mis-clicks, especially the two buttons on the left side, which are a bit sturdier. The mouse comes with a decently long cord with a gold-plated USB connection too; having used wireless mice I must say I prefer this setup to changing batteries, rechargeable or no.
When I first considered buying, I was stuck between this and the Microsoft Habu, mostly because the latter has two additional buttons and a left-to-right tilt wheel. I've tried both, and I must say this is clearly superior, not just in price point but comfort as well. You don't really need the two extra buttons unless you plan on switching the DPI a lot, and according to ESReality's Mousescore 2007 the mouse performs far better in 1800 DPI than 900 or 450, so it's probably better to stick to the highest DPI and change the sensitivity instead. I can't say I miss the left-right tilt wheel either, since the scroll button's click function is a universal scroll in web browsers, and that's just as good if not better.
$45 seems a bit expensive for a mouse, but even for non-gamers, consider how much you use it - it's probably 99% of all user input to your computer, so why not splurge a little on an excellent mouse? Razer is also apparently moving into mice/keyboards/etc. with a general computer usage focus, so those non-gamers out there should check out other Razer products as well.