Originally Posted by Brian
My advice would be:
1. Yes, make damm sure it's breathable
2. Get one with hard boots attached
3. And most important of all, make sure it is fitted with a "comfort zip".
I agree 100% with Brian on this.
Drysuits are expensive, and compared with conventional waterproofs take a minute or two longer to put on and take off. Having a neck seal can take a bit of getting used to as well (but if it's sized correctly you'll not notice it after a few minutes).
However, whatever perceived disadvantages there may be, if you want to guarantee that you stay dry then you need a drysuit.
I started off with a "waterproof" flotation suit, because I didn't feel that I could afford a drysuit. It's certainly warm, and it's reasonably resistant to water, but it doesn't keep you dry like a drysuit does. With hindsight it was a mistake and I should have bought a drysuit straight off.
My next purchase was a non-breathable drysuit. If the price is right and you're not planning to be wearing it all day, then one of these is still better than a flotation suit for keeping you dry.
Finally I got a breathable drysuit. I've had it for five years and wouldn't go back to anything else.