The Boss ME-50 is a guitar processing unit and full effects pedal. Included effects types: tone modify (EQ), compression, noise suppression, reverb, overdrive/distortion, modulation, delay, expression pedal effects-- all for under $300 brand new.
Back in the late 80's and early 90's when this type of effects processor was first created, a much larger and heavier unit was less capable and cost about 4 times as much. This being my 3rd floor effects board in my musical career, I have some comparisons to make over time as technology has become more efficient.
'Pound for pound' as the saying goes, this little machine packs the greatest punch all things considered, again including price. The best aspect of it though in my opinion is its usability. It works less like a computer as past super-complex units have, and more like a touring kick-board. It's manual setting is where it shines best by allowing its user to simply and easily access and modify any parameter without bending down and cycling through menu after menu with a guitar on his back during a gig. The external expression pedal too, is great. It is a kick on and off while the off mode doubles as a volume control.
I am really happy with the sounds I get out of this board and the quality it gives for the price. Any one can figure this board out in a day and that is revolutionary in the history of these multi-effects processors.