There is not really any operator overloading going on. You can implement Monoid for your data structure, but as long as you follow the laws... well, you are implementing operations in the correct way, there is no abuse there, nothing that's surprising and going to bite whoever is reading your code.
But one thing where Haskell errs, in my opinion, is in allowing arbitrary infix operators with random ASCII characters, which library maintainers take as an encouragement to each create their own DSLs which totally makes sense to them and nobody else, but that's not the same thing as saying that Haskell-the-language has a huge syntax. Maybe that's what you mean.
Yeah, have you seen what the Scalaz guys are doing? The operators aren't even ASCII! Apparently, there's something about monads that absolutely requires weird symbols.
But one thing where Haskell errs, in my opinion, is in allowing arbitrary infix operators with random ASCII characters, which library maintainers take as an encouragement to each create their own DSLs which totally makes sense to them and nobody else, but that's not the same thing as saying that Haskell-the-language has a huge syntax. Maybe that's what you mean.