Like caindiana, I applied to around 10 schools on PTCAS, so I can't say I wish it didn't exist. It did make the applications much easier, especially for the recommendation letters. I felt bad giving my recommendors 3-4 forms for other schools, I couldn't imagine giving them 10 more!
I also have had horrible experiences with their customer service through both, email and phone. Sadly, I've found that posting on here is much more useful. So, although I wouldn't want PTCAS to be gone, I would like them to get much better, and more friendly, customer service reps. By far the worst customer service I've ever dealt with..
Other wise, I agree with caindiana - reading the directions and checking over your app is extremely helpful. After dealing with their customer service, I knew I didn't want to rely on them to fix a mistake that was my fault.
However, when they told me my app was verified and to check it over - I did find a mistake. They put my Nutrition class was 3.25 credits instead of 3(I printed my app after I submitted and it said 3, so not my fault). They fixed it right away, but I do think I missed a mailing date because of it - oh well. They also made a mistake on my verification last year - put that my anatomy class was an English class or something.
PTCAS is new so these little things will probably get worked out in the next few years, hopefully.