In reality, not all that much different from the UA-ordered Airbus fleet that has two lavs on the aft left hand side of the aircraft around door 2L. I think the transverse galley across the entire aft bulkhead with lavs on either side forward of the doors is a better configuration, but we know why UA went with the SpaceFlex layout.

I didn't spend much time back there but I did not find lavatories themselves to be unusually small. I did not visit the mid cabin lav. The F lavatory felt a bit more spacious.

With all that said, it is a very nice airplane with a decidedly premium feel. I was pleasantly surprised.