Could you describe in more details how you got burned? (I have never done anything big in haskell)
Specific problems were extending a program to do "just one more thing", as is commonly the case for more "scripty" tasks. This often caused severe refactoring, as what was suddenly a simple function or IO/ST monad now had to include another monad and it all would become a bit of a mess. In general I find combining monads in Haskell pretty unpleasant, especially when you consider that this kind of stuff is so trivial in other languages that you don't even think about it. To put it shortly, I would spend too many brain cycles wrestling with Monads and strictness and Haskelly concepts, and too little on my actual problem.
But hey, that was some time ago and YMMV.
The productivity curve for Haskell is exactly the opposite of something like Python. You spend a lot of time at the beginning writing all your fancy types, monads, etc. Then later when you have thousands of lines of code you can make non-trivial changes with the ease with which you could write a tiny one-off Python script.
It's a fantastic exercise to get to that point in Haskell, and the skills carry over in surprising ways to conventional languages too, so I unequivocally recommend it to anyone with at least, oh, say, 4 years of experience in "conventional" programming, to get you to the next level of programming skill. But make no mistake, it is quite the learning curve. I think this is a positive thing, though... the reason why it is such a learning curve is precisely that you are learning, in exactly the way you really aren't learning anything when you pick up your fifth object-oriented imperative language.
Then you actually have to use it for a while.