I chose Titanium for a serious application, although one that does not use the camera. I think there are a variety of things that could play into your decision...
If your app intends to do "fancy" stuff with the camera, or some real heavy image processing and so on, you're likely better off going native. If on the other hand, you just want to have it take pictures, and then those will be used as-is, or sent to a server, or what not, then Titanium should work just fine. Titanium does have some processing and image manipulation things, but as others have said, if you really want to take advantage of the device's hardware, you probably want to go full native.
It should also be noted, and Appcelerator says this as well, that with a Titanium app, you won't just write a single app that works as-is on all devices. You will need to taylor the UI to each device (or class of device, i.e. iPhone, Android), because they have different UI's, and different standard UI flows and so on.
But, one of the potential advantages to Titanium is if you don't know Objective-C and/or Java, and you do know JavaScript (and in my case, I'm actually using Coffeescript :). Or, if you would enjoy your work much more writing JS than ObjC/Java. This was one of the main reasons for me. I have done some ObjC dev in the past, and don't even mind it, but this project I'm doing is on a very very aggressive schedule, and it was just going to be far more effective for me to use Titanium. I was able to get set up and build an app extremely quickly, and I am not spending any time having to become more deeply familiar with the programming language I'm using, memory management bits (you can't fully ignore this with Titanium, but essentially they're doing it for you). Based on the folks I've talked to, and how much time they spend with memory management, Interface Builder issues (this is mostly the ease of forgetting to setup connections or hook various things up, IB is actually a pretty great tool), and so on, I'm quite glad I'm using Titanium.
While I expect to do an Android version at some point, it's not a priority. But, I'm glad to know that a large chunk of my app code will be re-usable, tested, etc. and that I'll wind up mostly just building/revamping the UI for Android, not rewriting networking code, data management, and so on. Android support will be much better (supposedly) in Titanium 1.5, but you may want to wait for that release to evaluate Android if that's a priority.
Finally, Titanium does have a "module" system, that allows you to wrap native code, exposing it as a JavaScript interface in Titanium. We are about to leverage this to integrate a third party library, and at least for what we need, it looks very easy to use, and has given me a little more confidence that if some particular native feature we need access to comes up, that we'd have a decent chance of integrating that while still using Titanium, but I think it would depend on what the particular native functionality was.
Good luck and enjoy building a mobile app, it's pretty fun!