First, I'm a big fan of 3D...but let my offer you a down to earth opinion.
I always look at 3D as having 2 parts to it. First: the part where objects pop out of the screen and scare you. The second part is were there is an onscreen depth perception. I have always been pleased with the second part in any 3D movie I've seen. The first part has always disappointed me due to the lack of.
Avengers had a few times of the first part... enough to make me twitch once or twice, but seemed average compared to other 3D movies.
I'd say stay your course, If you don't really care for 3D movies then don't spend the extra money. If you like 3D movies and have the extra money... see it.
ooppss...just re-checked your post. It seems you may have seen it already