I started out with the Mares Puck. I think I got it for less than $200 off Amazon. Granted it's not the Puck Pro, but I think I can give you what I did and what I didn't like about the Puck which probably translate to the Puck Pro.
Likes
1) Easy to set up
2) User replaceable battery
3) Display was easy to follow, everything you needed on one screen
4) Though I ended up turning off the alarms, plenty of alarms if you need them
5) Nitrox compatible
6) If sitting idle, never did go back to default settings (some do and I've seen people have some short dives because of it)
Dislikes
1) I couldn't find a bungee mount adapter for the computer
2) I like my computer more on the forearm, couldn't really do this with the "watch-style" band
3) The one-button became a total pain in the butt, especially when working in the dive log section (this really annoyed the crap out of me)
4) I had to replace the battery one time, and the plastic cover was too soft and it got messed up trying to get the cover off. Had to buy a new cover too.
5) In low viz you have to hit the button to get the backlight on (not a huge deal, but an annoyance)
6) Requires a Mares cable to get data, they are expensive, although there are threads on how to make your own
Do I regret buying the Puck? No , it's become a backup computer/loaner to friends for me now. However, I think (no evidence) there are probably better computers around the same price range.
Good luck, hope this helps.