I love GMail now. It took me a while to get used to the conversations idea, but now I love it. If I'm trading back and forth with someone, it's nice to have all 20+ emails in one list, and see who replied when to what.
The only other thing that I've never really like much is the lack of folder organization. Sure, labels are great, especially when a conversation falls under more than one label, but still doesn't sit well 100% with me.
Other than that, I'm really enjoying it. And having my email easily accessible from anywhere is great [the key word is "easily"].
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Matt