Interesting. I've never had a problem using it. But that does not mean that others have not had a problem.
What criticism is there of the current map?
Mostly the recent changes that have put all the new Overground routes on it, making it very north-east heavy, particularly with the lack of differentiation between the Overground lines. Another issue I've heard about is how the step-free access has been put onto the map, again mostly centred on one part of the map, the DLR.
Personally, I don't have a problem with using it, but I agree that it is getting rather cluttered now which I think is the main criticism I hear about it.