I mean that as a whole it's daunting and feels "unfriendly" to a lot of people. The heavy use of operators is part of it, but it's more than that. Haskell gets really abstract, which is cool, but it's hard to think about. Like I said, even monoids and monads seem hard to people learning Haskell despite being really simple. And look at the FAQ on that Lens library — it's an abstraction on top of things that are already pretty abstract in Haskell to offer "a vocabulary for composing them and working with their compositions along with specializations of these ideas to monomorphic 'containers'". That's cool and I really don't mean to criticize it, but it's undeniably esoteric and abstract.