We love Gmail. It's our lifeline. But there are a few major hangups that cause us to bang our heads against the wall day after day. One is the lack of a proper IMAP idle process for true push support and proper use of labels on Windows phones. (Yeah, there are decent third-party solutions out there. We're talking about native, out-of-the-box push e-mail.)
The other issue is contacts, which Google finally is starting to address. From the official Gmail blog:
Up until now, Gmail only supported some contact fields. Whenever someone imported their contacts from apps like Outlook and OS X Address Book, we used to put fields Gmail didn't recognize into the contact's notes section. Based on feedback from you, we added support for more contact fields (like birthday and website) and now store each of these fields separately, which makes syncing and round-tripping your data work better.
There you have it. We're getting there. Still not perfect, but better. (Insert "beta" joke here.)