It's a mixed bag: the calendar app is much improved but email feels like it's taken a step backwards: you have one app for all your mailboxes but it shows each email account as a distinct entity. I rather liked the idea of linking email accounts so I could have one mailbox for my main account and have my secondary accounts in a linked mailbox.
Settings is somewhat more confusing with a series of submenus; it's harder to find what you're looking for sometimes.
I've also found that it sucks the battery dry pretty quickly.
Other than that I don't see a huge change on the overall user experience.
Meh...