My company uses ASAP in order to manage swim lesson registration across multiple locations throughout the Greater Houston area. Through some custom programming the staff at ASA were able to tweak their software to streamline participants into the registration for only their pool, and keep all other locations hidden, to eliminate confusion.
The support staff at ASA are very fast to respond and are tireless in their efforts to solve any problems that occur. So far, those problems have been the result of user errors, which the team has helped fix as needed.
With a web-based registration system, I have complete access from any location I am at so I can constantly make updates and changes to any registrations on the spot.
The program features for ASAP are detailed and can give you as much information as you need in a variety of packages.
While I really love using ASAP for my registration needs, it does have some limitations right now. The software is constantly being updated and improved though, so I don't expect these limitations to stick around for long.
A drawback is that while you can send email through ASAP to your program participants, staff, etc, it uses a web-based email that doesn't store the sent messages. I would like to see an interface that ties into the email system set up on the user's computer, such as Outlook or Thunderbird, which would allow the email sender to store the messages for reference purposes.
Lastly, the only other drawback I've come across is that the system is not fully functional on a BlackBerry or other smart phones. You can get fairly detailed, but cannot get down into the class detail to view individual participants.