It’s true, you could do almost all of these effects using apps. There are dozens of retro-fi photo apps on the store, most of which cost a couple of dollars or less. So if you intend to shell out $30 on this thing, you need to really mean it.
On the plus side, switching between effects with this puppy is going to be faster than any app can offer. Plus, you can concentrate on the photo’s subject while you switch, rather than the on-screen camera controls of whatever app you’re using. And the other benefit of hardware filters is that you can use them with any photos app you have installed.