This low-cost function generator is simple, but perfect for many hobbiyst use cases:

-You're learning about analog circuits such as amplifiers, filters, ADCs, etc. and you want to try example circuits.
-You want to test test low-frequency designs analog circuits (amplifiers, filters) for your personal projects.
-You want a small, portable function generator that you can keep in your laptop bag.
-You want to learn how a DDS (Digital Direct Synthesis) generator works.

Its interface is really simple, three knobs and a button, so if you're a novice, you wont be overwhelmed with functions you'll seldom use, but thanks to its communication interface, you can generate relatively complex patterns involving different frequencies and waveforms using an external controller (e.g.: an Arduino board).

One possible improvement would be to be able to change frequency units so you don't have to introduce 10 000 000 Hz to generate 10MHz, for instance.

Regarding signal quality, it has very little distortion up to about 10MHz and you can get quite decent sinusoidal waveforms up to around 15MHz (the maximum frequency allowed is 20MHz).

The build quality is quite good, definitively better that those no-brand chinese function generators that you can find in Ebay or Aliexpress for less than 100€. The electronics components chosen are high quality, I'm particularly happy with the feel of the knobs.

It is a completely open source design, so you can rest assured that if you fry something in the future, you'll be able to repair and change any component easily.

In conclusion, if you're on a budget and looking for a function generator, I 100% recommend this one.