I just have to mention Zinio e-magazines again, because I keep being so impressed by how excellent that service is. This is so rare. (For example, the Wall Street Journal app, I just can't use, it is so non-intuitive.)
The billing is easy. The magazines look perfect. Seriously, you can zoom to your heart's content like a well-done PDF file. (Perhaps they do use PDF, why not.)
And the internal links from the the Contents page work too.
Last year I gave up my last subscription to paper magazines because I rarely got around to reading them. But for some reason I enjoy reading on my iPad more, and I now have around half a dozen subscriptions via Zinio which I really enjoy having. I hope this company is doing well and will survive and expand.