The hard thing about the IMC is staying ahead of the aeroplane IMHO. Once I got a reasonable scan going I didn't find it hard to fly on instruments, but workload management is difficult. Flying an approach you're flying the aeroplane, identing things, talking to ATC (and fiddling with the radio when you're told to contact someone else), looking at the approach plate, watching MDH/MDA and doing pre-landing checks (...but not always in that order
). You've got to stay organized and ahead, otherwise things rapidly go wrong.