When I learned Haskell in college I was blown away by how laziness enables cool things like dealing with infinite lists or more performance even though the UX is exactly the same. (Apparently with Ruby there is the slight hint of adding the lazy method in between)
Later I found out laziness in the whole system by default leads to some difficult issues, which quite a few people seem to agree with. Simon Peyton Jones (Haskell co-creator) apparently has said "The next Haskell will be strict". (https://news.ycombinator.com/item?id=14011943)
That was SPJ being cute more than an actual indictment of Haskell fwiw. That quote gets misused a lot.
Laziness hasn't killed Haskell's usefulness. However, it is something Haskellers take for granted. I can't tell you how many times they "just turn on -XStrict" and are surprised their program gets slower.
Later I found out laziness in the whole system by default leads to some difficult issues, which quite a few people seem to agree with. Simon Peyton Jones (Haskell co-creator) apparently has said "The next Haskell will be strict". (https://news.ycombinator.com/item?id=14011943)