Sound — 9
I've got a cruddy cheap Gibson Les Paul knockoff guitar, and the worlds worst amp. Yet! The sound quality is still fine, the loop sounds exactly how I played it with absolutely no stuff ups or problems noticed. I don't know what people are saying about this gentle hum from the pedal but I don't hear anything and I have a bad amp as well, besides in 99% of live situations it would never be noticed anyway. I really love the band Battles (math-rock band, very loop based) so I did some research and found out they use this exact same pedal! And I notice the similarities in the sound of the loops, very happy.
Overall Impression — 9
This pedal is great for any kind of music really. The fact it has a mic/aux/instrument input is great and allows it to be used with synths, keyboards, microphones etc. If you are considering getting the newer model the RC-30 I would tell you to ask yourself a question of what is more important. If you want a loop pedal that is ideal for recording over live performance with stereo, in built effects (the effects suck!) 3 hours recording time and more recording capabilities then the RC-30 is more for you. If you want a trust worthy pedal that is in my opinion much better for live performance and overall use. Used by many popular bands, and has been loved by musicians for years because of the intuitive, simple and trustworthy overlay, I would highly recommend the RC-20XL. P.S. The reverse effect (not on the RC-30) rocks, sounds trippy as love it!
Reliability & Durability — 10
Its Boss so you know its strong as hell, it feels tough and sturdy. I wouldn't sweat if I dropped it a few times by accident. It did not come with a AC power pack but I'm not fussed because the battery compartment looks sturdy and tough encased with a black metal lid. I would much rather use this over the newer RC-30 loop pedals, I've read a lot of other reviews of the RC-30 and have heard that it skips randomly sometimes and has design faults with the quantize and tap tempo, yet there has been no faults said about the RC-20XL and I'm not expecting this thing to muck up anytime soon.
Ease of Use — 9
I love this pedal so much, it has everything I need in a loop recorder pedal, just close to perfect and I've only had it for 6 hours so far. After having a dull read through the manual I decided to just get stuck in and muck around with it. Its very simple once you get the hang of it, it may take you around 20 mins before you start to understand the pedals features and functions, but its not Rocket science.