First, and very importantly for my sanity (and aching back), the City Mini is super easy to fold one-handed and carry up our narrow stairwell. With just a pull of a strap on the seat, the stroller folds slimmer than my Snap 'n Go
Also good: The stroller has the extra maneuverability of a three-wheeler, but it is still slim enough to fit into the tiny shops and bodegas in my Queens neighborhood. And, while it doesn't have the amazing all-terrain power of our larger Jeep Liberty stroller
The sunshade is huge and amazing and keeps the sun out of Andrew's face at all times--though, when the sun is highest his toes and sometimes his hands get a little sun--and it has two open and close-able clear windows to check out what your little one is doing. Just be careful about leaving the peekaboo windows open in direct sunlight or sun will pour through onto your baby's head. Also, the seat fully reclines to accommodate a small or sleeping baby or serve as an emergency changing table.
Finally, I am just in love with the orange and gray color scheme of my City Mini. Andrew is traveling in style!
Now for the bad: The seat of the stroller has minimal back support, a little bit better than an umbrella stroller. This is a problem because Andrew ends up slouching in the chair (which looks uncomfortable, but he doesn't seem to mind) and throws off how I set up the height-adjustable shoulder strap of the 5 point harness. I hear tell that you can buy an additional support for around $8 from Baby Jogger, but I haven't tried to yet. Also, I had a bit of a hard time tightening and loosening the harness straps at first... but maybe I am just a spazz?
Also, the stroller storage basket could definitely have been made bigger (there's room for it), but as it stands I can't get even a medium-sized diaper bag into it. I have to hang my bag off the stroller handle, which you're not supposed to do, but which doesn't tip the stroller if it isn't too heavy. And if you want a parent console with a cupholder and a belly bar or child snack console it needs to be purchased separately. Boo!
And, finally, I wish the stroller handle telescoped out. I know that it is as short as it is so that the City Mini can accomplish its amazing fold-in-half feat, but the shorter handle means that even I at 5'4'' sometimes kick the axle when trying to look through the sunshade peekaboo window. My 5'10 husband hasn't pushed the stroller yet, but I have an inkling that he's going to be kicking the axle a lot (and yelling about it).
Wow... that seems like a lot more negatives than positives, but I do feel like the good points are so good for me that they outweighs the bad. I can live with a small storage basket, having to buy a belly bar, parent console, and back support because I really need a good quality stroller that is light, easy-to-fold, and maneuverable with an extended sunshade. If you don't live in a city, though, there are sure to be better stroller options for you.