It is as Vesh says, it's actually a combined program and is shorter than the traditional route (4 years undergrad + 4 years dental school), which is a huge plus.
My thoughts on them? Well, I agree it is an excellent way to get into dental school, though it requires a lot of discipline and focus. Sometimes people change their minds about what they want while in undergrad, so there's that as well.
There are drawbacks as well, like inflexibility in studies, most programs won't allow you to major or minor in whatever you want, it's often a required and obviously accelerated biology track. Then there's the fact that you're stuck with one school, so you had better be sure that's the school you want to attend for 6-7 years.