You can disable storing media to your photo folder. That was the first thing I did after installing it. I've never had issues with support on wifi, and that's a large amount of my usage of it.
Its killer feature was what it did before it was acquired by FB, really not much difference since then. The killer feature was international messaging without SMS/MMS costs (and poor reliability) and only needing a phone number, so you could take it with you easily as you moved through devices so long as you controlled the same number. This got presence around the globe making it easy to message almost anyone, almost anywhere.
Its killer feature was what it did before it was acquired by FB, really not much difference since then. The killer feature was international messaging without SMS/MMS costs (and poor reliability) and only needing a phone number, so you could take it with you easily as you moved through devices so long as you controlled the same number. This got presence around the globe making it easy to message almost anyone, almost anywhere.