Notes

This baby has 3 main features that make it a very good deal:
1. Versatility (from overdrive to distortion).
2. Compact and Lightweight.
3. Price (around 35$ including free shipping from China).

The first two are especially important if you're on the road or very limited on space but still wanna have analog clipping in your signal chain. Other extra sweets are: true bypass, cool design and the presence knob.

I own this pedal myself, and although it's often labeled as a distortion pedal, it is capable to sway from a very subtle overdrive to a pretty gainny distortion that is way above classic rock crunch. Comparing it to the BOSS DS-1 though, the Joyo JF-39 has smoother, rounder crunch, whereas the DS-1 sounds sharp and abrupt with more presence.

In order to dial in into an overdriven sound with the Joyo, roll back the gain knob to about 8-10 o'clock and set the pre. knob to 11-3 o'clock.

Strange but turning the presence knob clockwise adds some boost-overdrive along with the presence, while the gain knob controls the amount of distortion, both these knobs are very interacting with each other, the presence knob can boost the distortion.

In my opinion the Joyo Deluxe Crunch is better suited for lead guitar playing and not for crunchy riffs though, despite of its name.

Example Settings

(position is indicated in space relative to the numbers on a clock's face)

Overdrive
pre: 2:30, volume: 12, gain: 10, tone: 12

Nice Lead Tone for a Single Coil Bridge Pickup 
pre: 12, volume: 11, gain: 2:30, tone: 11

Moderate Crunch
pre: 12, volume: 11, gain: 12:30, tone: 11:45

Pleasant Distorted Tone for Soloing (neck pickup)
pre: 12:40, volume: 12:30, gain: 1, tone: 1:30 + (optional boost) 

High Gain Distortion
pre: 2, volume: 11, gain: 5, tone: 12