With just the "Guitar" voice slider up, and the trigger set to something above zero, then it sort-of becomes a plain filter, but it isn't envelope-following, it's merely envelope-triggered. Each time you play a note hard enough to trigger the filter, it moves through the full sweep you've got set at the rate you've got set. If you don't play quite so hard, it doesn't sweep at all. There's no middle ground. So no: If you want an envelope filter effect, you won't really get it from the BMS.
+1 to what kevteop said (without the Trigger slider up, you get nothing at all... and you'll need to have at least one voice above zero). It's rather "clean" if you dial in just the Guitar slider, but it may have a few uses for you. Combine it with some ambient effects, and you can get some cool "laid-back" synth tones.