Speaking as a nasty little gnome myself, I think the escape artist is worth it. I use it in nearly every battle. feet frozen to the ground? escape it. feet entagled thorns? escape it. rogue peel you off his healer? escape it. etc etc.
The size thing is nice as well in large groups (AV). I've hidden myself under/in an enemy tauren in the past as I attack another horde...priceless.
Human abilities are nothing to scoff at either, I just haven't taken one high enough to get the full benefit yet.
In the end, it is of course what you prefer. (I have a bunch of gnomes, so I am a 'little' biased toward them).
Edited, May 2nd 2008 9:10am by Quintor