I use either a Strat or an SG for guitar and either a Mesa Boogie Mk II or a 50 watt Marshall stack for amplification. I do experience noise especially if the amp is on the lead channel. I used to get a lot more noise when I had a Boss SE-50 plugged into the same electrical strip. Since both the Zoom and the Boss had wall wart power supplies I think they interreacted and created noise. I also began plugging everything into a Furman line conditioner and this seemed to reduce the noise further.
The effects are a mixed bag. Some are very good some very weak. However with tweaking, most of the effects can be made usable. The chorus, flanger, and leslie effects are rather weak and artificial sounding. But combining these with overdrive and delay etc. can still result in good sounds. I have read other writers comments that the wah was no good. I was able to get a decent wah sound by tweaking the parameters and adding overdrive and other effects. I use the Zoom pedal which plugs into the 8050 control pedal. With that setup I can program the pedal to control all sorts of things besides the wah. That is perhaps the best feature on this product. I was disappointed in the tremelo. I was hoping for more of a Fender type sound. With a Fender, the tremelo speed stays constant no matter what you play into it. With the Zoom the tremelo is triggered somehow by the notes you play. If you play several faster notes the tremelo sort of stops until you slow down again. In the meantime the tremelo has lost the rhythm. Its not a bad sound but hard to keep that tremelo rhythm going as it should. The pitch transposer is typical of less expensive effects units and I find it ok for guitar. I don't think the Zoom sounds as good as a Digitech 2101 or a T C Electronics G force but those are much bigger units and cost much more.
I have used this without backup for several years now. It did break down once at home and I sent it off for repair. It took a few weeks to get it back. I have never had any further problems with it.
I use the Zoom for various types of music from blues to alternative grunge to psychedelic. It is very versatile. If anything happened to it I would consider getting another but I would also consider the later 9050 which has a build in tuner and a noise gate. When I got the Zoom I tried the ART and Digitech models that were available at the time. Those also sounded good but did not have the variety of effects that the Zoom had.