I find it kinda fun riding up and down curbs, and over stuff that makes most roadies swerve madly out of the way. But then I might not be able to do curbs even with 25s.

My most lasting impresion (so far) of 23s: I went for a ride with my boss(geared). I remember pedaling down the hills at the same speed he coasted. On the way back I remember marveling at the tiny size of the tube as he changed a flat.