Well, it's a very nice unit. I like the size, have had no problem with controls (except for the D-Pad being kind of squishy) and the screen is to die for.
The volume is sadly very low, much lower than any previous GBA I have played with. I suppose this is to safe battery life, but I would have liked to hear it abit louder.
The control pad feels abit mushy as stated earlier, and the system definitely feels more fragile than the SP or original.
I REALLY like the idea of the faceplates. Not only do they change the look of the Micro, but much more importantly, they protect the screen. Scratch up the screen (which is really the face cover), no problem. Replace it and you are new again. This should have been done a long long time ago.
The system is light...I mean VERY light. Almost feels like you aren't holding anything. Very comfortable for this reason.
The screen is awesome. It just looks so nice. You just have to see it for yourself.
Sure, you can get the newer SP (with new screen) for cheaper than the Micro. But I have never really been into flipscreens myself. Some may disagree with that, but that is my take on the subject. The Micro just feels good, and brings back (at least to me) what a portable should be like. It's lightweight, the screen is fabulous, the controls are perfectly responsive, and it is small...a very small game system...nothing else. It does what it should, and has true portability written all over it.
All in all, I love this device. This is quite possibly the best portable game system I have ever owned all around...and it is still a GBA...amazing..