Contrary to some users, mine is not dead quiet and I'm using humbucker equiped guitars. With the noise gate on it is dead quiet but on clean patches you can hear the gate cutting off the hiss which I hate hearing. The level of noise also depends if you're using the compressor or not. Compared to my Zoom 3030 it is only slightly less noisy. Over all I am kinda disappointed. I heard lots of people saying that this thing smokes the Zoom 3030. When I tried mine out, it sounded pretty darn good on a KMD tube combo amp with a Hammer Special tele-clone, but going through my Crate and Dean Markley halfstacks, and with high-gain humbucker equipped guitars (mainly my Washburn Dime 333), it didnt sound quite as impressive. The presets were all way way to trebly, many of the clean patches distorted the processor's digital section (which I fixed by lowering their level), and my expression pedal needs adjustment because it is not going reaching its full range of motion or something because the volume wont shut-off completely, and the whammy function wont go back to the original note. I had to take off the little rubber pads on the lower end of the expression pedal and even then it still is a tiny tiny bit off. I've also noticed that on a few clean digital patches I hear tiny little pops. I havent determined though whats causing this...could be my cables or becuase I have it plugged into the same surge protector as my computer system. Finally we get to the distortions...Grunge is pretty good and I was able to get some reasonably rich metal sounds, Heavy Sustain wasnt too bad, though the heavy sustain sound on my RP-1 seems to sound better, and then finally theres overdrive which in my opinion just plain sucks. The overdrive is a nasty digital sounding, hard clipping mess that to me sounds like its overdriving the digital section. I did get an almost passable overdrive sound but it still was pretty crappy. I dont mind edgy overdrive like on my Danelectro Daddy-O, but unlike the Daddy-o the RP-10's overdrive just completly lacks balls and harmonic richness. One thing I did find however is that the sounds noticably improved when I used the cab simulators straight into my mixer board. I think it makes a cool home recording processor, which may be the only reason for me keeping it. Oh another beef... I couldnt believe there was still a big ol' gap between patch changes! Still just as bad as the original RP-1's gap between patches. In fact my Zoom 3030 has less noticable gaps. I don't think theres worlds difference in the general sound quality of the RP-10 over the RP-1. I'm assuming also that the RP-12 isnt a whole lot different sounding. Over all I enjoy my Zoom 3030 much more as it has a better wah-wah (though the RP-10 has a cool talk-box sounding auto-wah), has better and much more versatile distortion sounds (try getting a Big Muff sound or a Type-O-Negative type growling distortion distortion sound on a RP10 or RP12). The RP10 might be a little more pristine then the 3030 but it also still colors the sound in a very noticable way. The 3030 just seems to have a warmer more earthy vibe 1to it and also much better cab simulators. The cab sims on the RP-10 are barely adequate and thats only with massive parametric eq'ing to the patches. Even then the cab sims dont add any richness to the sound, they only seem to just round off some of the treble frequencies a bit. Still though you can get some good clean direct sounds and some interesting direct distortion sounds.
Hmmmm....look pretty durable except for the power plug which I keep envisioning breaking if somebody steps on it just right. MY RP-1 is built pretty much the same, and it whent through hell and back on gigs so I expect the same from the RP-10. I take a backup always.
Over all...if you're planning on getting this or an RP-12 or RP-6, listen to them if possible on a amp and guitar similar to your own. Then try messing around programming the sounds to see if you can get sounds that you like. Also compare it very closely to other effects processors. In my opinion the Zoom 3030 is a much better deal if you dont need midi functions. The Whammy effect is smooth, but doesnt track well at lower octaves, and a good Floyd Rose tremelo still kicks its ass. I would not buy this new nor would I buy it again if mine was to get stolen or something. I have, however, tried the big Digitech 2101 and 2112 and those to kicks some serious ass so if you got the bucks go for those...Anyways mayabe it'll suit your tastes, maybe it wont...all in all not bad of a processor, but nothing totally mind-blowing either if you've already used many other processors before.