User error here. You don't take the picture by touching the screen, you take it by pressing the camera button all the way down.
The reason it is slow is because every time you touch the screen, you're telling the camera to refocus on the object that you touched. The camera then refocuses on that area, optimizes it, and takes the shot.
I do know *why* you're touching the screen -- it's because that's the way the Android OS has always done it. But it's wrong on WP.
I think a lot of the problems that iOS and Android people have with Windows Phone is that it's not iOS or Android. Frankly, as a WP guy, I had the same problem on Android, and when I was a heavy webOS user in 2009/early 2010, I couldn't pick up any competing device without using my thumb on the bezel to swipe backwards and forwards.
A big piece of the adoption of a new platform is the learning curve you need to take for a couple of weeks. You need to understand the theory behind the UI and how it works to get the most out of it. That means coming in with an open mind, and figuring out how the UI theory addresses your needs (rather than the other way around).