I've never used them myself, though I have ordered custom profiles from other sources with varying degrees of success. If you only need to profile one or two paper types and aim to keep the same printer for several years, I think it makes sense to use a service like this, while accepting it may take a week or so until your profile arrives.
If you plan on using more paper types or different printers, it would probably save you time and money buying a spectrophotometer and making your own profiles at home. You would have the up front cost of the calibrator, but it will also work for your displays. Apart from that your only expense is a sheet or two of paper when you need to create a profile.