Polyblit is one of the synths I've used most frequently. Being based mainly on free synths, this is one of the most important and versatile synths in my humble arsenal. why? well, to begin with, this is one of the best substractive synths available. and I'm not only referring to free synths. The thing has got 3 oscillators, every one with all the possible and usual waveforms, and all enroutable to 4 lfos (!), filters, etc In that way, you are able to create almost every possible sound: pads, basses, strange effects... It sounds very analogue, and I would compare it to the Polysix.
It may lack onboard effects, and that may make you think sometimes that some sounds are too plain. Add a reverb and maybe a delay and you'll be blown! you'll see it can compete with many of the best soft synths available.
I like the GUi, it's very clear; it's not completely easy to use, since it has a lot of commands and modulation routes, but it's worth the effort.
The presets are many and good, they cover pads, basses, etc
And the price...well that can be tricky. When we talk about synths that cost ehem... 0 euros, we are usually inclined to make allowances. Well, forget about allowances here. This synth is one of those you're amazed they're free. get it, you won't regret it.