We absolutely adored ours, she was a really nice dog - and we'd never had such a small dog before!
They're tougher than they look and very intelligent, so learn quickly.
We now have a third poodle (15wks old and a standard) the first was a miniature - all have been girls, none of them ever chewed furniture, and were housetrained quite quickly -one in 6 days. None have been snappy either. They love being with people, and all of ours have liked children. They're moderate walkers, and many don't like being on their own for extended periods. The current one has never so far barked at visitors or the postman, but the other two did until told to stop.
As with other breeds, they have particular genetic or health issues if not bred to high standards. You can read up on them on breed specific sites.
Yes, they are lovely dogs - at all sizes (this standard we have is a bit of a bouncy handful though at 15 weeks! :) ) - we've had the same groomer for 16 years now. He comes to the house every 4 weeks, and I prefer that someone else does it, but many people learn to do it themselves. Ours was quite tiny, and I could scissor trim her easily, but never tried clippers.
Cost will vary, but expect £20-25 (perhaps less depending on groomer) for shampoo, dry, toenails and clip - perhaps ear cleaning every few months. They'll usually need grooming every 4-6 weeks depending on your preferences & the coat, and I brush ours to keep dust out every few days or so. If a bath is needed inbetween, it's quite easy to do.