Let me let you in on a secret: I suck at email. Chances are that if you send me an email I'll read it within an hour or so, but it's replying that gets me. I usually end up either responding to your email in the first two minutes, or it gets sent down into the pile of email in my inbox, which can delay a response for weeks (or even a month or two in some cases).
I love having my email with me, though. I run everything through IMAP, which, if you aren't doing it already (and are stuck on POP accounts), you really should. It's a great help in keeping everything current between multiple Macs, my phone, and web-based email.
The problem is that I don't want to be bothered with spam, and I don't want to have a gigantic inbox on my phone. It makes me happy to check my Mail.app on my iPhone and see only a couple emails as opposed to a laundry list chunk of emails that have built up.
Moving to the iPhone has helped me in both those areas. For one, I finally moved some email accounts around, retired old email accounts, and developed some new spam-fighting techniques. It's really annoying to be sitting around, get a new email notice on your phone, and when you go to check it you notice that it's just another spam email. So it was my desire to get rid of that inconvenience that led me to take those steps. In turn, it meant that my desktop experience was happier, too- there's less spam interrupting me at my desk, too.
The real problem, though, is workflow. Within a business, the sooner you can respond the better. When I do respond quickly to emails (ie, within 5-10 minutes after it was sent), it really makes a favorable impression on the person with whom you're corresponding. There's hundreds of varying ways to handle this problem, most of which never really worked for me, but I finally found that I just like the feeling of a clean inbox. When I can go into an account and see absolutely nothing... it's just very refreshing. That becomes my goal. It means that I don't settle for "well, I'll just reply to all of them except for these two". Keeping a clean inbox means nothing stays behind. I can easily verify this on my phone, too, which provides more motivation.
There's other ways of helping you do this, too: adding new folders to prioritize responses (a GTD-esque sort of way to handle things), offloading common email (which I like to do... if I can get an RSS feed instead of email I'm happy), and so on.
Personally, I still don't like email. I wish there was another way to handle it. But in the meantime, it seems like we're stuck with it. In some respect, it's like there's a race going on between all email users on who can manage the suckiness the best.