It was my first computer, and I still use it as a back up on technical dives. It's an extremely reliable unit, and is a excellent in timer mode as it has mins:secs. The user replaceable battery is good, the battery life is fantastic, and as far as the 'old' LCD screen goes it's one of the best - big clear numbers.
The one button thing never bothered me. It's ok to use, but obviously takes longer to cycle through menus as a result. Logbook can be frustrating, but that's post dive; it's during the dive the puck excels.
I only changed as my wife bought me an xdeep bt, but the puck is always in a pocket on every dive. I replaced the strap with bungee which really lowers the profile too. I'd recommend it, I've done all my recreational diving using it, and many tech dives in timer mode; good job.