The purpose of this type of device is not entirely clear to me.
It is neither a particularly accurate multimeter nor a "real" oscilloscope (it doesn't even have a BNC connector or anything like that).
Mustek has many similar models with very similar specifications.
I don't even think they're "bang for the buck".
If you want such an all in one device, I would spend $30 more for a
Dso3d12 which offers
much more in every way (And unlike other brands,
two oscilloscope probes are included btw).
However, I prefer separate gear. In the entry level segment, a AN870 plus a DSO2512G, for example, is a good value, in my opinion.