some questions are pretty good very very similar, some are just outrageously easy. My score on pcat practice was very similar to real one. If u haven't done that much practice or haven't invested too much money in it, go for it.
The questions were very similar, it was not timed, and it gives you a large score range for which you might fall in on the real test (all mine said like 76-99) which is kinda pointless. I would do all your studying first and take the practice test a few days before the pcat and time yourself, because you will need to work very quickly on the actual PCAT.
I did both of them and think they were beneficial. I used one of them as a prognostic test when I first registered for the PCAT then did the 2nd one a few days before the actual test to measure my improvement. I also figured out how much time per question was alloted then timed myself to see how fast I needed to go. I've seen too many people say they had to guess on lots of questions during the actual PCAT, which probably comes from lack of preparation. Timing your practice tests should help you avoid that.