As long as they are more like Trees/Ents and less like Dryads, and can be killed 3 times, coming back stronger each time.
I actually like the dryad look. The concept art does look more like an ent, though, if that's the case I'd keep my eyes peeled for a mod that makes them look like the ones from http://www.tesnexus.com/downloads/images/15073-2-1202044166.jpg or http://www.oblivionportal.com/info/images/spriggan.jpg. If you've ever peeled the bark off a dead branch, the wood really does look like smooth, pale skin.