Tube Booster is a tube emulation. I found it through a KVR-search since I was looking for something thta would provide a more overdriven sound than lamphtruster. of course, psp vintage warmer would come into ones mind for that purpose. But then, VW is expensive and also a compressor. what is more, I think it's much better to have the two separate: a tube sim and a compressor. so I searched and found Tube Booster.
How does it sound? I did an a/b test with VM and I found Tube Booster to even sound better when it is not driven too much and when the eq is adjusted properly. I think the presets are just ok and do not show the full potential of this tube sim. tweak it according to your taste and you will be amazed.
the GUI is not bad, in fact quite functional, but it could be improved. if TB looked more professional people would maybe easier realize that is an absolute pro-level sounding vst. (unfortunately, it is like that: looks count even in audio).
there is no doc provided but it's not really needed so I did not cut the rating too much.
customer support: not needed so far.
stability: great so far.
value for money: unbelieveable that this is free.
addition: I made some presets, you can download from here: