There are plenty of reviews & demos on YouTube.
From what I understand, the calendar is very good with a miniminist look, the contacts are pretty good (now they added selective Facebook contacts rather than all)
The email client is also very good, although lacking some features like unified inbox, threaded messaging (like Gmail) and doesn't support Gmail labels. The first two have been hinted at as being address via software update and only excluded due to lack of time to write the code. As for Gmail labels, I wouldn't count on them any time soon. I believe the top features of email are multiple message management (i.e. selecting/moving/deleting more than one at a time, and also the pivots allowing you to easily swipe through all, unread & flagged messages
The common theme with all 3 is they integrate back to the "cloud/server" if you add FB, Hotmail. Gmail, Exchange and I think Yahoo.
But take a look for yourself, as what I think is pretty good may turn out to be crap for you.