I got the 1530USB a few months ago - took me a while to find a good setup and to get the time to do it, but I'm having quite a good rate of success converting and preserving my childhood C64 tapes, which have been sitting in a garage for 20ish years. In fairness most of them are the same Italian newsagent ones mentioned at reply #2, but somehow I prefer doing the work myself, the fact the .tap files come from my own tapes having somewhat of a nice feeling.
As I said, I had to fumble with the settings a lot - as a matter of fact I have set the recording level to 0, which however is still almost in the "red zone" on Audacity. The .wav files are then converted using Audiotap - Inverted wave form, advanced values top to bottom being 0,12,44100,20. The second value in particular seems to be extremely important - 12 seemingly a sweet spot. With these settings most tapes work, with the odd game not loading in Vice (but often, the same game doesn't load on my real C64 with the same 1530).
Other than making .tap files, I'm also extracting .prg files to use on the real C64 with an SD2IEC - a process that is surprisingly effective!