If by wet dome you mean the WetMate, for the price it is definitely worth it.
I'd say, any kind of wet dome is better than the housing mere front glass, which, as brilliantly demonstrated by Interceptor121 in his blog, only allows for unpleasant distortion and very reduced field of view.
If you are looking for an all-purpose video dome, it's a winner if you are constrained by budget, weight and space issues.
Having said that, you probably want a wide angle dome port if you need to frame entire wrecks and/or whaleshark-alike-sized animals.
I shoot footage for my own stock library, plus every now and then do short two-dive productions for customers in the dive centre and sell it as a souvenir video. For that purpose it does the job properly.
I could use a wider lens for Manta cleaning stations, groups of grey reef sharks and the occasional big spotted one, but I am more than happy with that.
Here's also an example of some still shots I recently took as part of a souvenir package for some customers doing a Discover Scuba course. All the shots in water are made with the WetMate mounted and natural light only.
