I used the gmail mail app for a little while until I realized it couldn't do a couple of simple things, then I junked it.
It wouldn't show your quoted message when you reply or forward. I don't have a short memory but when it's a lengthy email I need to respond to point for point, it becomes a nuisance. Secondly, you couldn't select/copy/paste from the email you are currently reading. Most of the time, I ended up forwarding the email to a different email account just to copy bits of the email.
It's a great app if you're reading your email but in terms of creating it, it's very rudimentary. Tell me I am missing something or if you see or know of anything different from what I'm doing wrong.