Does what its supposed to do.
Look, we all know that this is nowhere near $500 or $1K mic pres but its not supposed to be. Its a good all around mic pre with a tube (!) and phantom power. Its low voltage so you aren't going to get high voltage mic pre flavor out of it. But what it does, it does well as long as your expectations are in check.
Sound: Clean to dirty with the right mix of input and output gain. My unit is low noise even with the +20dB switch on. Its not perfectly quiet but its quiet enough for vocal work in a busy mix. Face it: you might have to do some editing in post to get the sound you are looking for. Thats called "creativity". As a basic mic pre or tube DI (especially for guitar into Amplitube or GR5) you can't beat it. I've tried a few different tubes in it. Stock, Mullard, and JJ. The JJ sounds the best to me but overall I can't say there was a HUGE MINDBLOWING DIFFERENCE.
Ease of use: Unless you can't read everything is clearly labeled. Even the knobs give you a certain visual representation of overall dB gain. This is perfect for a first pre because you might actually learn how a pre works.
Features: +20dB of gain is great for mics like the SM7B. Phantom Power for your condensers. Phase reverse. Output Protection Limiter for those of you recording direct to computer through a cheap soundcard line in or something similar.
Bang for Buck: Lots of neccesary features. Decent amount of gain. A tube you can replace to change the sound of the unit. XLR and 1/4" ins and outs (mono). VU meter (its useless use your ears). LED clip/power indicator. Aluminum case. Small form factor. Its alright for $20. Its a down right blessing of technology.
I use my Tube MP in my laptop setup. I have a desk with a laptop and NI AK1 interface. Works well for coming up with ideas that have usable elements in my basement studio. Even finds its way into my studio when I need something nasty to work with. Its worth $20. It does a decent job if you are creative with its use. Simple. Buy it, let it sit on the shelf for a bit, then bring it out when your $500 mic pre just isn't doing it for you. You might be surprised.