Pros
-Very very good functionality: it works as a wireless gamecube AND vc controller, which is unprecedented, and the response time is excellent, no lagging
-button remapping
-optional rumble that is very strong
-It has a nice feel
Cons
-Everything is very tight, small, and close together: sometimes my thumb hits the left control stick when I'm using the + pad, and I have had more than one case of hitting the remap, turbo, or slow buttons while using the control stick. This is REALLY annoying, as it will result in weird things randomly happening , like a button suddenly not working, or the start screen suddenly popping on and off rapidly, etc., because you hit a button without realizing it. Just remember that if you are going to get / use this controller, you will need to be precise and pay attention when you use the buttons / sticks, if you don't want things like turbo and slow getting activated, which are really rather useless buttons anyway. The controller would be far better off without them. And would it have hurt to move these buttons up to the empty space at the top of the controller, rather than right in between the sticks where you're likely to hit them? I don't think so.
[Edit] - Over time, maybe it's just that I've gotten used to it, but my thumb hitting the turbo, map, and slow buttons isn't really a problem anymore. However, I still will have the occasional instance of hitting the slow button, usually during an intense gaming session. But the point is, you get used to it.
-The shoulder buttons are TERRIBLE, for gamecube or VC. It only registers as a full press if you push it down really hard, which is what you will have to do for VC games that use the shoulder buttons. For gamecube games that often use the sensitivity of the buttons, you will have to be really precise with how far you push it down if you want it to work. Pressing a shoulder-button partway doesn't read as a partial press, unlike the wavebird, when you first press it there's a dead zone, and then right before you reach the point where it's fully pushed in will it briefly read as a partial button-press. This is difficult to perform, but at least it's there.
-A couple minor quibbles to top it off - the control stick's sensitivity isn't ideal - when you first start to tilt, it does nothing, but then it starts to register, at relatively high sensitivity. You'll need to be precise. Also, the + pad does not feel as high quality as I had hoped it would.
[Edit] - The tightness & sensitivity of the thumbsticks is a little bit more of a problem than I originally thought it to be - you will have to have VERY precise thumbs in order to get the kind of precision needed for a game like timesplitters 2. Also, the rubber on the sticks wears off and has begun to peel off. Room for improvement here.
Additional Thoughts
You cannot save button remaps, every time the controller turns off or goes on standby mode (5 minutes of non-use) you will lose any button configuration you have set up. I didn't list this as a con, though, because the button remapping is easy, fast, and intuitive, and most controllers don't even have it as an option - so it's a welcomed addition. Also, keep in mind that when you turn the controller off the LED light on the receiver will blink endlessly, so the best option is just to always leave the controller on, as it will enter standby mode and neither controller nor receiver will flash. Another note - I was using the controller once when the light on the controller suddenly started flashing and it stopped working - I was severly frustrated as I was in the middle of an intense round of smash bros. However, I learned that this is an easily solveable problem - just press the connect button - and this has only happened once, anyways. I might've accidentaly pressed the connect button or something. To top it all off, this is a very useful controller due to it's unprecedented functionality and feature set, it just suffers from some flaws that can be annoying at times. The pros outweigh the cons, and I would definitely recommend this controller (especially considering the price). Just don't expect perfection.