I have the service -- no complaints at all. You pay only for what you use -- that is, 1 month at a time (if that's what you want). $10/month and the service is great.
I have the latest outlook, so it's no big deal for me. However, I don't even really use the integrated email -- I've been sticking with the BWC. It's more useful for me for the IPPP service book.
I also haven't tried the webmessenger service through them yet, but I'll let you know how it goes.