I was pretty sure that, being an avid walker, I wouldn't have any trouble transitioning into these shoes.  I heard that they wear you out at first, but I didn't think it would be too bad for me.  I was wrong.  These kicked my ass initially.  I'd get home after a day of wearing them (including a few miles walking), and I'd be beat!  Didn't last long, though.  Now I wear them almost every day, and while they still work my legs out, I don't get worn out.

I think this particular shoe is decent-looking.  All black is always a pretty safe bet.  Some people don't even seem to notice that they're Shape-Ups.

These have helped my posture.  I've long been prone to slouching, but I walk and stand much straighter in these.  I also noticed a change in my gait right away.

Bad things:
Balance.  You have to get used to constantly balancing in these.  If you commute on a train (as I do), and have to stand, it will be markedly more difficult.

Running.  I don't think these shoes are designed to be ran in.  I hate running myself, but since I take public transit it's sometimes a necessity.  I've strained my upper leg surprisingly by running in these.