Carrick is a good player, really good player. But I'm not sure he's the type of midfielder the munsters need. Mind you, anyone is an improvement on O'Shea and Fletcher. Whether Carrick will be a great signing will be determined by whether or not there are enough funds for another striker and midfielder to play alongside Carrick & Scholes.
I know a couple of seasies at Old Trafford and it must be said they are totally uninspired by this signing, but time will tell.