As a newly certified diver then, the dive shop recommended a Suunto Mosquito. Within a few months, the unit I purchased, for no apparent reason, conked out on me. Because I was about to leave for a week-long liveaboard, the proprietor lent me another Mosquito while mine (under warranty) was shipped overseas for repair.
Then on the very first dive, I discovered that the Mosquito-on-loan didn't work either (what are the chances!). I spent the rest of the multi-day, multi-dive trip simply staying at the same (if not slightly higher) level underwater as our DM. Imagine not being able to calibrate on your own especially when there's, say, a ray in a crevice that needs you to descend a little bit longer.
Eventually (it took longer than a month if I remember right), I got my Mosquito back, and six years later, all it needed since was the occasional change of batteries. Being a purely recreational diver, I have not really felt the need to change this model for another.
It's all so random, I tell ya So, for the new diver about to commit to the model of his choice, also make sure that your shop (mine did try) goes the extra mile for those "just in case..." moments that are bound to happen.