I was looking through some X1 reviews... One even complained that the car had one problem -- it was too close to the X3 without being an X3. Needed more comfort and room, I think they were suggesting! I think BMW "fixed" that with the new X1. ;-) I would disagree -- the X1 is about the right size I'm looking for. Any taller, and it's not going to handle as well, any bigger and it'll just be slower, etc.
Most reviews seem positive, although many don't like the styling much. It does have some odd styling, but I'd call it more "quirky" than anything too negative.