RegOnline has been well-suited for providing registration for participants as well as payment options in the same place. That is literally all that my department uses it for, and it is very well-suited for this purpose (though pricey). And although it is pricey, it was one of the only approved options by my university to accept credit card payments for our annual conference, as other options could not be properly tracked by the university. So for this purpose, RegOnline is very well-suited.
I think that if someone needed to build an event registration page that did not require payment options as a necessity, then RegOnline would be less suited for use. It still can easily track participants, but I think there are better options out there for those who only need the most basic of services.
I also think that since RegOnline has provided additional formatting capabilities, that it does handle the registration pages better than it has in the past. However, these still need improvement, with the ability to rearrange the order of required and optional questions.