Aside from the convenience of cordless (I'm now trying to kick the habit of constantly moving the now non-existent cord out of the way), there are other reasons to like this controller. Some complain about the weight, but it doesn't seem too heavy to me. With the batteries installed, it has just the right amount of heft, making it feel solid and well-built. The controls are smooth, accurate, and well-placed for my thumbs (I have somewhat large hands). There is no cheap plastic feel, and the slightly textured plastic case is pleasing to the touch. The rubbery tops of the thumbsticks provide a secure grip for your thumbs.
With wireless, I was worried about lag, but there is none perceivable. Action games play fine where timing is critical. A nice touch is the ability to quickly swap the D-pad and left analog stick via a toggle button right between them (with corresponding indicator light). That makes it easy to go exactly straight forward when you need to. Because although there are slight centering guides to keep the thumbsticks centered horizontally and vertically, it is still very easy to move off to the side. That's not a complaint, as I think analog controls should allow you to move in any direction easily.
Only two complaints:
1. When releasing the thumbstick quickly, its self-centering action will often overshoot to the opposite direction for a split second before settling in the center. It is enough to turn the game character around. I've had to get used to releasing the stick more gently to avoid this.
2. Macintosh software is not included nor available from Logitech's web site for customizing buttons. The included software is Windows-only. I was disappointed when the D-pad was not automatically recognized in certain games. I figured I could just configure the game's controls to perform the appropriate actions, but the D-pad is not treated as buttons and not recognized at all. However, I was able to solve this by using the shareware "GamePad Companion" to assign keystrokes to the D-pad.
Analog <-> D-pad toggle
Thumbsticks act as two more buttons
Excellent battery life (seems to be true to the advertising claim of 100 hours with vibration off)
No Mac software