I think the combo vaxes have positives for many families seeking less jabs, less visits to doc (less copays), and stuff like that.
For us, however, I felt that, despite the possible benefits, we would rather have one shot per visit whenever possible and create our own schedule. We do DTaP, MMR, Polio and Hib (so obviously this particular vax wouldn't be for us, but still we would not do a combo).
I like one shot per visit because it's easier to identify possible reactions. Plus, while we do feel some vaccines (like polio) are important because of travel, we feel we can put that one off a bit. So, by not doing in in combination with a vaccine we like to get earlier (like DTaP), we are able to keep a delayed and selective schedule.
In addition, sometimes you can get three separate shots and still end up with less aluminum, for example, than the combo shot.