The GUI is quite nice and functional, just the readability could be better if the background wouldn't be such a dark colour though.
The sound is really good. To my ears BS-1 sounded best from all SF2-players I came across so far. Just the volume is a bit low sometimes with certain soundfonts.
For the features, it's all there that one may need to tweak when using soundfonts. However, I never got program change via MIDI working here and by the lack of a documentation and any customer support (see further down) I have to substract some points here.
Documentation... what documentation?! There ARE NO docs at all! I couldn't believe it, but it's true: Also after I payed for BS-1 I did not get any, nor a link to it. The only "docs" you will find are the short infos on the home page, that's all...
Sorry to say, but the support is just worse. All contact options you have is an email-address and I tried to contact the developer for three time but didn't ever get any response.
BS-1 is stable as long as you don't touch certain settings while the sound is running.
Conclusion: If you're in need of a cheap and good sounding SF2-player, go ahead but be aware that you won't get any help if you run into trouble with it. If you have some extra money, better go for VSampler or any other soft-sampler that loads soundfonts.