I think that some sites are packed with to many features that mobile interfaces do not allow to include all that stuff, and maybe still hard to define witch ones are must be keeped on that version.
I don't think it is optimized for mobile yet. It's not too hard to use on my tablets. When I'm on my phone, I just make sure that I have desktop site enabled on my browser. It solves the overlap, but you'll have to zoom and pan a lot.