just got this...
Gotta say, didn't really expect too much from this pedal. I have an old MIJ Arion flanger and it's neat enough but kind of one dimensional. I saw this pedal on eBay for $15 and just bought it out of impulse. I've always thought these Yamaha pedals looked cool. well, what do you know, this is a really great pedal. The shit thing about most modulation type pedals is that when you step on them your guitar goes all thin and reedy. This is not like that; it has a really deep lush modulation. It's made me reconsider Flanger pedals entirely. It's easy to get a great sounding chorus sound out of it as well as crazy-go-nuts siren noises. Tweaking the feedback knob adds harmonic overtones to the sound allowing you to get some weird sounds from steel drum sounding tones to almost organ sounding tones. The noisemaking possibilities with this pedal are really great; you can get all kind of dying whale noises and crap by combining it with delay and twiddling the knobs. You can add a hefty deal of clang to your guitar by putting it before your distortion.
That graemy fellow did an demo showing some more normal uses for it. It's a pretty good demo but doesn't really show the sonic mayhem this thing is capable of.
I had pretty much written off things like phasers and flangers as sort of cheesy 'sound effect' pedals but this is a much more useful pedal than that. I guess it goes to show that there are a lot of the modulation pedals out there that aren't very good. You have to really get a good one to get an idea of the functionality of these types of pedals.