I'm guessing you're an Android person. Have you run across apps that don't feel like Android apps? They feel like someone made a least-effort attempt to port an iOS app over to "the other platform" and the result is just sort of jarring and weird?

That's the issue. It's not necessarily that they look bad, your app can look like what you want. The issue is that they don't follow lots of little platform conventions that you get used to and so they feel foreign and slightly annoy you every time you try to use them.