Sound — 9
Most of my amps are of the better quality PCB based type (Egnater, PRS) which can still have a lot of hum and hiss associated with higher gain settings, especially at high volumes. This pedal has been a lifesaver for killing the annoying hiss from the preamp stages and pedals during rehearsals and gigs. I haven't been able to find any tone change when the pedal is engaged. The only tricky thing, as I mentioned earlier, is to make sure the gate is BEFORE any time based effects (delay, reverb, etc). Since the pedal senses your dry signal, it will cut off any sound without prejudice when you're not playing, including reverb decay and delays. The Noise Clamp may not be adequate for modern metal chuggers, who want extreme cutoff and note tracking - the gate does take a fraction of a second to kick in. But for anyone else, this pedal does the job very well.
Overall Impression — 9
This pedal works great for cutting off that nasty excess noise, and it does the job at a fraction of the price of similarly functioning units like the ISP Decimator G String. I'm definitely glad I went for this over a simple noise gate, I only wish I had gotten one earlier. There's not much else to say, if you have noise in your signal this pedal will cut it, simple as that!
Reliability & Durability — 9
I've not had any problems with this pedal yet. The jacks and switch all seem solid, and the casing is very thick and tough. I bought mine used, and the previous use didn't seem to have any negative effects on the pedal either. I don't have much experience with MXR products, but their reputation proceeds them and I don't foresee any problems.
Ease of Use — 8
The only tough thing about using the MXR Noise Clamp is the initial setup. It can be difficult to know which cords go in which jacks on the pedal, and where it should be in your signal chain, so I highly recommend consulting the manual during setup. It needs to have the signal running through it twice: once directly after your guitar, and again after all noise/hiss adding effects but before all time based effects. If you're trying to fix a noisy amp, the gate stage will need to be setup in your effects loop after the preamp(during setup, imagine your preamp as a pedal, this makes things much easier). Basically, this pedal works by sensing your "dry" signal right from the guitar (before any effects and added noise) to know when you're playing, and uses that information to turn the noise gate on and off, cutting off all that nasty noise when you're not playing. This is much more accurate than a simple noise gate, which has to try and differentiate between your playing and effects hiss and hum simultaneously. After setup, this pedal is a breeze to use. Just turn it on when you have a noisy effect or preamp on, and you're good to go. There's one knob to adjust the sensitivity to your dry signal, which is very easy to adjust to the correct setting. Due to the dry signal sensing, you will never need to re-adjust the sensitivity to compensate for how noisy different effects are.