I've had my DSO Nano V3 for 24 hours now and it is working for me.
Yes, the "manual" is crap. DSO Nano users, can we write one? A wiki (a real one, not Seeed Studio's) would be a great way to collaborate on this. Some arrangement would need to be made to deal with version differences. BenF f/w needs documentation too.
The user interface is cumbersome and difficult to learn (especially in the absence of a readable manual), but I am getting the hang of it. I have to say that the digital 'scopes I used years ago were not all that easy either, and they cost more than 100 times as much.
Is it a great 'scope? No. I figured, even before I ordered it that it might be comparable to the $5 multimeter (from Harbor Freight) that I use for my Arduino projects: not accurate, not flexible, but mostly adequate. It IS gonna let me do some things with sketches involving dynamic signals that I sure couldn't do with a meter, or even Mr. Gammon's fabulous Frequency Counter Sketch.
And the hardware and software are both open source, so I expect improvements, which I might even contribute to (If I can figure out how to cross compile for ARM).
I'm working on a (almost) sine-wave DC-AC inverter that's basically working, but I can't look at the output waveform without a scope.
I also had a look at the voltage across the LED in a Joule Thief (google it!) and was amazed!
And I'm really grateful to learn how to get that damned "Reference Wave" off the display, Thanks!