Have mostly used it on a Strat (single-coil, of course). Have also used it on an Ovation electric-acoustic and a Danelectro 12-string. The rundown for each...
Stratocaster: Easy. Apparently humbuckers are preferred, but... I don't like humbuckers, so whatever. But single coils work just fine. The Ebowed sound is so huge and overpowering. It makes the guitar sound pretty huge and monstrous. Since the thing isn't really an effect, it's a way of *playing* the guitar, it's definitely consistent (though it can be a pain maintaining the perfect amount of pressure at first). Harmonic mode is gorgeous (fun to switch between harmonic and normal from run to run... the transition sounds very *interesting*). All of the bowing and imitation sound way better (and are much easier) on an electric 6 string!
Acoustic: Not as easy. Unplugged, the sound is obviously very thin. Needs to be amplified. But plugged it, it's insane. Lots and lots of great under(over?)tones. Not as controlled as a single-coil electric, but definitely earthshaking! With even moderate volume, it becomes very difficult to prevent feedback. So, of course, I just incorporate the feedback. Fun to Ebow one string while mutting all others but one or two, and letting specific strings feedback along with the Ebowed string (which itself feeds back a bit, especially if you stay on the same note). Also gets a bit of fretboard buzz, and when the strings really start going crazy, a buzz against the Ebow. Takes some control to make it sound orchestrated and not chaotic... but once you figure it out, it's amazing! Bowing and such are very difficult though, for reasons stated above (not even power if unplugged, too much if plugged in). But sounds great just sustaining!
12 String: Again, great for sustaining, a pain for anything else. Sounds especially amazing in the harmonic mode (abeit kinda piercing). The Ebow doesn't fit the strings, though, so you really have to be extra careful and exact to get a sound/not have the driven strings hit the Ebow. There is no just light resting it and casually moving it along... your right hand movement has to be very exact and deliberate. But once you get it, the sound is amazing. Especially sounds great to let the high string play and the deaden the low string, then release the low string and let it come in (gets this weird meaty/swooshing analog synth sound), or vice versa of course (to slighty different effect and a bit more difficult to control).
But overall sounds great. The horn sounds aren't too convincing, nor are the woodwinds, imo. They sound good for what they are, though. But the string/bowed sounds are very precise (not perfect, but close) and could definitely pass for strings during live performance and whatnot. The harmonic mode is wonderful, and I can't imagine an Ebow without. Has such a dreamy but cutting sound, and really exciting to have such controlled AND sustaining harmonics! Basically, the thing's great. Can play the strings on something like Lou Reed's "Street Hassle" or create the ambient pink bubble of a band like The Church. Very versatile for such a simple little device. Nothing's like it.