I use the APDL on my Treo, and on a CLIE' before that. It has saved my A$$ several times, especially when Scheduling tried to get me do do something that would have put me over on a time reg. it also has features that allow me to track expenses, check as to whether or not a trip trade will work or not, maintain door codes etc. It's well worth what I paid for it. The one thing I'd like to see put on it is a revision tracker, or log.