Yeah, maybe (although I find it OK after using it for many, many years now).
One thing cannot be disputed though. It is the most complete (in the enterprise sense) mail client for Gnome. It supports 3 types of native Exchange connectivity (apart from the usual open protocols), it can edit LDAP contacts etc. Once it gets completely ported to WebKit (which is under way), it will also handle dreaded HTML mail much better.
I also found Red Hat folks in charge of its maintenance very responsive (as part of Fedora). As long as you give them a backtrace (and they are very helpful in telling folks how), they will fix it.