I thought she did a very good job as T'pol, having to communicate emotions in such a subtle manner is bloody difficult.
I never had a problem with her acting, but everyone has preconceptions about how someone is supposed to behave, that's just a normal side effect of being human. That being said, Jolene hasn't really done much so it's hard to determining her acting talent, of course there could be a reason why she hasn't done much. lol.
Personally I think she alot better than some more famous actors I've seen.
And yeah Star Trek actor quality has always been all over the place.