It works! Idk about the whole tube screamer thing, the premise is it drives the circuit to make your tubes distort. But it also has its own distortion sound and millions of people use it with solid state amps. Regardless, it works and it’s a familiar sound.
The kit and instructions were great til the last 3 steps (fitting the LED was fiddly, the instructions switch between using the words 'shield' and 'ground,' the holes for the jacks were a bit small, and there wasn't any extra wire length for mounting the switch.) It was 5 stars until time to mount the LED, so I'd give it 3.5 stars as a beginner's kit. But the quality is really good, the sound is good, the option for a finished box with stickers for only $1.00 is great, the price is under $70 so overall it's pretty close to 5 stars.