I spent months reading reviews and examining in person all the major brands of strollers in preparation for my daughter's birth. Now that she's six months old, I wanted to share my thoughts about the ol' City Mini.
First, we live on the third floor of a walk up apartment, so we were looking for a stroller that was easy to carry, and not super expensive. The easy fold-up action is as advertised, incredibly simple and easier than any other stroller out there. But, it still feels somewhat heavy, and it's basically impossible to carry the baby and the stroller at the same time, which we had hoped would be possible when we purchased it.
Second, it's a little flimsy. Not as bad as the Combi or lighter McClaren models, but a far cry from the Bugaboo. Within a couple of months the wheels started to squeak, and it's just not as solid as you'd like your baby's stroller to be. We were worried about how the seat sways back and forth and doesn't have a hard back, which is still an issue, but we bought a Snuzzler, which has helped a lot. Also, as other reviewers have pointed out, the seat is a little awkward, forcing our baby to sit at an angle, and even when it's up all the way, she's still not perfectly upright and tries to move forward more. For some reason the shoulder straps are also nearly incomprehensible to everyone in my family, and we've had trouble adjusting them.
Finally, the positive things: I think it looks pretty sleek, it's very maneuverable, it is relatively light, and the canopy is awesome, better than any other stroller.
So overall, if you're looking for a relatively affordable and light stroller, go for it, but for a longer term investment you might want to shell out the extra cash (...four times as much!?) for a Bugaboo. If I could go it over again, I might do that, and hope that the Bugaboo could survive the stairs going up to my apartment!