Honestly, I got assigned the level of Expert by doing pretty much nothing.
I think it isn't a great representation of the worth of a user neither their commitment towards the community. There's no achievement needed to become an Expert!
The idea is actually good but doesn't work in my opinion (at least not with the current formula).
I know determining who's worth the title of 'Expert' can be tricky, so... wouldn't it be simpler if we didn't have this levels system?