I'm all for ambiguous endings, but...
The Lobster's ending seemed unnecessary to leave open ended. Of course I'm referring to whether or not he actually blinded himself. It could have ended with him returning to the table and us seeing he didn't do it, but tells he her did anyway that he did. It wouldn't change the impact and would have maybe even added to it.
I don't hate the ending, because it still has me thinking about the possible outcomes. But I guess I'd just rather have seen him come back so it is clear that he does love her and, even though lying about being blind, and didn't abandon her there or go back to be turned into a lobster like some other theories I have read. I really cared about Weisz' character and I wanted to leave knowing she was going to be okay and have support in her life. Not have be left with some doubt!
Still, great film, and either ending works for different reasons. Just my two cents.