I have mate & really didn't notice all that much difference tbh. Probably worth investing if you've got the spare cash but I don't notice enough difference to justify the cost unless I was doing a full monitor/printer/scanner set calibration.
Saying that I used a very good mac calibration program, I've no idea how the PC ones are.
Best to be on the safe side though so it's a good idea to see how it differs to your present settings - there may be a massive difference :shrug: