Overall, it seems to be a fairly decent e-mail program. It does have a few things about it that annoy me, though.
Primary among them, is the ~/evolution/ folder. What in the hell is up with that? Why does it need that, and why does it create it without asking me? Why isn't it called ~/.evolution/, and why does it appear that there's no way for me to tell it to use ~/.evolution/?
I've been seeing this more and more frequently lately, particularly among KDE/Gnome apps, and it seriously annoys me. Don't clutter up ~/ with crap. I don't want it there. Use a dot-directory, or give me the option of where I want it located.
After exiting Evolution, I deleted ~/evolution/. I don't expect I'll be starting it up again anytime soon.
 For those who haven't heard of it, Evolution is an E-Mail program for Linux. It's fairly similar in appearance and features to Outlook.