I remember when I tried a wireless mouse years back and it was horrible. It did not feel responsive enough in games. Should I consider buying a wireless mouse if it otherwise seems good?
I've had no issues with lag/responsiveness, but this is very hit or miss depending on the user (the same reason why some people use gaming CRTs).
The only downside I've had is that the batteries make the mouse a little heavier, which causes faster fatigue for long periods of gaming.
Also, you run the risk of batteries dying on you in the middle of a frag fest.
Wireless mice can be fine for gaming if you spend enough. I purchased a Wireless Logitech G7 5 years ago and used it for competitive gaming with no problems. I never had interference, never lost connection (as far as I can remember) and its response was great. But I also paid for that. I think at the time I spent between 60 and 70 dollars on it.
Something you may want to ask yourself is: do I play games so competitively that it's not worth the risk of interference or loss of responsiveness? If you're competing or just fear the thought of that happening, then I'd get a wired mouse. Otherwise, spend a little more, do some research and you'll be fine.
Hope that helps.