I use Nokia messaging, and i think you did an excellent work. Congratulations!. Really good!.
I used the symbian email inboxes, they worked, but they had no fault tolerance and any problem with the connection ruined the automatic inbox checking..., so now i am really happy with my email. I use it with gmail, yahoo, two corporate emails that are hosted in email servers that i administer..., so it is GREAT. Is as good as your rival RIM, well i think a liittle better because you can have it with multiple phones (i have) and with Blackberry Internet Service you can't, you are limited to 1 phone at a time.

Despite the great job, hotmail is still missing. I'm not particularly a hotmail fan (i rather use yahoo or gmail), but hotmail is a huge player in the e-mail arena. You just can't miss it.