The Analog Discovery isn't a very good oscilloscope (only 5Mhz bandwidth) but it can do a lot of other stuff. It's sort of a bus pirate plus Saleae plus Oscilloscope all in one. As a learning aid it's very useful. Once you've outgrown the tutorials though, it's not much use as general purpose 'test gear'.
Just as an FYI, the -3dB bandwidth of the AD is over 20MHz. (stupid marketing decision to advertise it as 5Mhz IMO - see
page 16 of the technical manual for more info I can attest that with the BNC adapter and real probes it is very usable at 20Mhz.
I agree it is not substitute for a "real oscilloscope" but no USB scope is IMO. That said, the usefulness of the AD extends way beyond the tutorial as you say.
I have a lab in my basement with a Rigol DS2072 and several analog scopes as well as other assorted test gear. Yet for many projects - such breadboarding, or debugging an arduino, MSP 430 or other MCU project - I use the AD at teh desk in my home and find it pefectly adequate for those kind of projects. Also, e the network analyzer is very useful and not something duplicated in my lab by a seperate instrument.
For the academic or even full price, I think the AD is a great purchase that most will find useful even once they graduate to full fledged instruments.
Hey, maybe Digilent needs to put me on the payroll of their marketing dept....