Summary: It's not an awful mouse, really. I give it 2 stars simply because it's both less comfortable and less accurate than a $13 Logitech from Wal-Mart. Now, I didn't pay much for this mouse ($25, if I remember right), and I mainly bought it because of the DPI and the customizable side buttons, but I had come to expect a smooth, accurate cursor. On the jerky/inaccurate cursor: This reminds me of how the joysticks of an old Madcatz controller I used to own worked.
Summary: I bought this to replace my old Sidewinder mouse. To my disappointment, this version feels very cheaply made compared to my old one. It is all plastic, and there is no weight adjustment. You know how there are special, hamstrung versions of GPUs made to sell at dept stores like Wal-Mart? This is the mouse version. I changed my review from 3 to 2 while writing this because I realized how truly disappointed I am.
Summary: The mouse wheel for this mouse started sticking. Also, the three dpi settings buttons in the middle were too easy to hit accidentally while using the mouse, so I ended up setting all three to the same dpi. I ended up replacing this with a mouse from Logitech, and it doesn't have any of the same problems. I've used the replacement for at least a year now, and wish I had saved the money and just gone straight to that.
Summary: I'm unsure why others feel the vertical side buttons are a great design feature. I think they protrude too far from the mouse and I often find myself accidentally hitting them. For obvious reasons that causes a lot of problems in-game. Moreover, while it could be due to the fact that I've been using a Logitech G5 for the longest time, the vertical positioning of the side buttons does not feel comfortable. Overall the mouse feels cheap.
Summary: This mouse is responsive as any other gaming mouse on the market but you have to be a mouse palmer with big hands. This thing is like pushing around a brick, it's huge. The verticle side buttons are awesome but can sometimes be hit by accident when lifting the mouse to reposition it. If you have a big hand go for it, but if you have small hands go with a Logitech MX518.