I just spent 3 nights at the Four Season Miami and I highly recommend it. The rooms are spacious and bathrooms to die for.

I had a package overnighted to me and the hotel staff was on top of it the entire time and even tracked me down to let me know it had arrived.

In typical Four Seasons style they go above & beyond and will try to cater to any request.

If you're looking for a place to just relax and sit in the sun, this is a great hotel. The pool area is large and when we were there (mid april) not too crowded at all. The pool-side service was pretty decent (not as good as other Four Seasons I've been too) but it wasnt bad at all. The food was good, but like anywhere, gets old after a few days.
Warning: this is out of the heart of the action, downtown Miami is practically a ghost town. If you want action, do not stay here! But South Beach is an easy 15 minute cab ride ($30 each way).
The room was very nice but "standard". One king bed. sort of small, great bath. Ask for an upgrade. Who knows?

Friendly and professional service on par with or better than the Ritz Keybiscayne, Ritz Southbeach, and Ritz Coconut Grove. The Four Seasons two hotel guest pools are large enough for relative privacy in the low season. The pool area is much larger than the Mandarin Oriental's small infinity pool. There were more children than expected in main pool area, and children are segregated to one pool the Ritz Keybiscayne. There is no beach, and the Brickell area is quiet. Housekeeping had a few hiccups which they promptly fixed when we called. My wife loved her massage, and the gym is excellent. Expect a $30 cab to SOBE where we had a superb dinner at OLA in the Sanctuary. The location is fantastic if you have business in Miami, just be aware of the distance if you want to be in the thick of it in SOBE.

A great hotel for a quick getaway for some sun.

We stayed at the Four Seasons for 3 days and it was perfect. Amazing pool, great service, nice, spacious rooms. Kid friendly.

The hotel is in the business district so the neighborhood isn't 'happening' but there are some great restaurants within 3-5 block radius of the hotel so you aren't stuck with hotel restaurants only.