The iphone scores poorly in the email department. And its so bad that I have to continue using my Blackberry. The only commendable advantage that I can see is that it does HTML mails and that it automatically fetches your emails when you first run it. Reading simple mail attachments are fine, including office documents. Push mails are OK for Microsoft Exchange and fair for Funambol users.
One annoying thing I find unsatisfactory is the Contacts. Apple just does not allow you to type in an Alphabet search for names but forces you to scroll up and down that few hundreds contacts alphabetically sorted. That's bad.
Another worth mentioning weakness lies in her virtual keyboard. Despite the "intelligent" word correction feature built-in, just makes composing long emails or text messages frustrating. In fact, it constantly over-suggest itself, thinking its smarter than the user. Phone does not default to the dial pad, which most people expects, but stays at the last accessed menu. Notes does not allow simple categories to sort each of your notes and resides in one long list.
As many mentioned, text messages still cannot be forwarded, and it still lacks a fundamental copy and paste function. To top it all up, a simple search is absent on the device, making it a brick when information search is required.