Logitech PS2 Cordless Action controllers are great while they last. I think I could easily wear one out in less than 3 months consistently. The X, square, or any other button you use a lot begins to stick after a while.
The controllers are basically like those disposable cable remotes back in the 80's. You pay the cable company for using one each month. Once the remote wears out they just get you a new one.
I'm now going to be on my third Logitech Cordless action controller. When a particular button's rubber pad wears out, the button just stays down in the low hole and doesn't pop back up right away. The X and square buttons are most common with sticking because they're the most often used buttons.
Games like the Onimusha series are quite hard on the controllers do to many rapid button presses. I had one wear out on the original set of batteries while playing Onimusha 3. The X and square buttons both would stick so it was nearly impossible to play that game that way. I'm quite sure these controllers never would hold up to the NES era games that all required pressing each button rapidly.
Anyway, I do like the controller while they work but unfortunately they become unusable right when you're about to break them in. NES, Game Boy, SNES, N64, PSX, and other PS2 controllers don't have this problem. Although it could be the pressure sensitivity thing that caused a design flaw but then again Dual Shock 2's don't experience this. Still its too bad Sony doesn't have a wireless Dual Shock 2 instead of endorsing Logitech.