The bad side is documentation and small community I think.
I can't say that Unreal's community is bigger than this. Because I did not use it enough to ask something.
But, the documentation, it's the worst, that's for sure. However, I'm waiting for new documentation. I hope it'll be better.
I would say that, despite this, the UE4 and Unity3d communities are really active on both the "internal" forum and the external (known) sites like their subreddit.
The CE's documentation has improved a lot over the year, to be honest, but they "should" need some online courses(from Academia e.g.) that would greatly improve everything for the new arrival(and not only)