For recreational diving, a basic computer can work for what you need. It may not work well for what you want. Whether you choose a console, wrist 'puck' or wrist watch style basic computer (let's say maybe around $250 - 300 or so?), let's take a look at the optional upgrades you might like:
1.) Air integration. You look at your computer instead of a separate SPG for gas pressure remaining.
2.) Dive logging with download capability to a desktop PC. The computer automatically logs a range of dive parameters (e.g.: time to start & end, total dive time, maximum and average depths, how much nitrogen loading you had perhaps, course of dive (e.g.: did you 'sawtooth' up & down a lot?), water temp.s, did you make ascent rate violations going up too fast) and, if it's an air-integrated computer, probably your start & stop gas pressures & calculate your SAC rate for the dive. On your home computer you can then add details like dive site name, dive destination, boat, etc...
3.) Intuitive interface. If you've ever had to change settings on a cheap digital wrist watch vs. an iPhone, you know the power of interface. Something like a Shearwater or Atomic Aquatics Cobalt 2 with an intuitive interface will cost you. But imagine you're on a dive boat, realize you forget to set your computer to a nitrox mix and...wonder whether you can figure out how to make the change. On some computers, not a problem. Others?
4.) If the dive computer can download the log to your desktop system, do you want to have to use a cable or have it happen wirelessly? Can it download logs to your cell phone? (I'm not sure which if any do that now).
Other considerations:
1.) Do you want an easily swappable, common battery so you're always ready to go (e.g.: AA?), or a built-in rechargeable battery because you live in fear opening & closing the thing is going to flood it with salt water & ruin it?
2.) How long is the battery life? I know at least one computer had a bad rep. for this (hello, Lynx). Computers with the big, multi-color displays and intuitive interfaces are the ones where this might bite you.
3.) Whether & to what extent a 'conservative' dive computer is undesirable has been debated in multiple threads on Scuba Board. I wouldn't want a Suunto for this reason, but many like them. Make up your own mind.
4.) For some things, it's better to go ahead & buy what you'll eventually want. If you're the type to tends to upgrade every few years because you want the latest bells & whistles anyway, and you'll probably buy a new dive computer in 6 or 7 years regardless, then 'starting cheap' isn't such a problem.
Richard.
