Let me put an Oz (well, sort of) perspective on this.
The late, much lamented Ike of Ikelite really worked very hard at after sales service and his widow has carried on in the same vein. Sure, people like Aquatica probably have the same level of service but then Aquatica housings also, as a generality, cost about twice as much as Ikelite equivalents. Equally there are others whose service is legendary, as in not existing. Having said that, if you need service something has gone wrong and what experience I might have tells me that 99% of the time the problem is user error. I include my own (of course). I have only personally experienced one problem where the blame could be fairly laid at the feet of the manufacturer.
And so to other things. It's been said already, I simply want to emphasise it, that you need experience in this photography lark, particularly in buoyancy skills. In my experience most people don't (today) get those overnight. I learned how to dive a lot of years ago but I was already a keen spearo (spearfisher) and so I already knew the sea well so buoyancy was, for me, of little issue. That is, more often than not, not the case today. Having said that, I believe that novice divers will learn the rest of what they need to know, such as breath control (the list goes on), as they learn about buoyancy, which is why I think that buoyancy is the big one. I venture to say that no-one, and I mean no-one, can take (even) adequate photos underwater without proper buoyancy control. I've seen too many camera toting cowvboya floundering about to think otherwise, Please don't become one of those, it's not a good look and, more importantly, bad for the ecology.