Harley Benton Ultimate Drive

This is an inexpensive 'interpretation' of an OCD pedal, a rather popular overdrive/distortion pedal which is about 4 times the price of this.

Firstly why are OCD pedals so popular?
Well because it's a very versatile pedal that can do a (fairly) clean boost or can reach a great Hard Rock/Metal drive.
In front of a good tube amp you can use it like a souped up tubescreamer (which is a good analogy for the pedal as a whole) to push the tubes into overdrive.
It's fairly transparent (in that no matter how much it's distorting you can still her the notes and chords without it turning to mush).
Also when set right it can be very touch sensitive (especially for bass) in that when you play gently it'll stay clean but hit harder and it'll overdrive.
Another added bonus it that it doesn't really lose any bass frequencies when you use it on bass.

Secondly how does it directly compare to an OCD?
The short answer is very well indeed. It managed to capture all the essential OCD characteristics mentioned above.
No, you are not going to get the same sound from an OCD and the Ultimate Drive with all controls set to 12 o'clock, you will need to tweak the Ultimate Drive's knob a little to get the same tone and on the whole I'd say the Ultimate Drive is a little darker sounding (on both low and high settings).
The artwork on the Ultimate Drive will also divide people, I don't mind it but I can see why many wouldn't be able to get past that. It does feel like a colossal misstep putting such dividing graphics on this pedal.

In summary
It's a great OCD clone for a fraction of the price, providing that you can live with the artwork.

I needed a pedal that could add some sugar in various scenarios. Different Instruments, pickups, pedal chains. And this has been great. For years.
Personally I think the sweet spot is at the lighter end of the low gain.
I have had eye wateringly good tones from a low Harley Benton Vintage Overdrive stacked into a low Harley Benton Ultimate Drive into Harley Benton Tube Combo with Reverb and Delay. I've used it successfully as the main beef on a octave up + 5th Bass split into a guitar amp, set-up.
I do think it could be easier to dial in, I sometimes feel like a safecracker on a shower thermostat, but that is the sacrifice for all the good stuff you are getting for the amazing price.
If and when you get one, I urge you to resist your human programming to instantly see how many wasps you can fit in the jar, (The answer is loads) and try to dial it in at the low end for the beauty. After all, Less is More.

Summary: It adds a lot of low-end (bass tones) to your guitar signal, and it can get really noisy. However, it seems to go well with single-coil pickups (at least much better than humbuckers).

I wanted to have a pedal in front of my amp that has overdrive/distortion characteristics, specifically to use with humbucker pickups. Since this is a cheap option, and it has relatively good reviews, I wanted to give it a try.

First of all, Low/High switch doesn't change too much if you are connected to a cranked amp.
The pedal is quite noisy (both with clean and cranked amps), especially if the gain and level knobs are beyond 12 o'clock.
The worst part for me is that it adds a lot of low frequencies to your guitar signal i.e., it adds lots of bass tones.
When I tried it with humbucker pickups into a Marshall DSL, due to the nature of humbuckers, the bass response was awful such that I couldn't even tune it with the EQ of my amp.
Then, I tried it with my telecaster (single-coil pickups) into my Fender Twin. I liked that sound since it added a bass response on top of the brightness of my tele. However, I didn't plan to add a pedal to my 'clean' rig. So I returned the item.