I bought the Line 6 Relay as I had seen how it was supposed to be a good alternative to traditional wireless systems and allegedly gave as good a sound as a lead.
Having received the system and used it properly for the first time last night, I can say that I was impressed with the sound quality, which is the big plus of the system and why you would probably buy one of these in the first place.
The plus's for me are the simplicity of use (just plug in and go!) and the sound quality. I used the unit with my Les Paul (humbuckers) and my Charvel Model 3 (single coils) and it coped well with the change in output of the pickups and seemed to give a consistent signal, which was also really useful as on my old Samson system, you had to adjust to compensate for the input signal.
My negatives are around the construction really, The unit is plastic in the flesh and looks a bit flimsy. It will be interesting to see how it stands up to regular gigging. Also, the battery compartment was fragile looking, fiddly to open and especially to close, which could be a real pain if you need to change batteries in an emergency. My biggest gripe though is the belt clip, which is removable so that you can position it horizontally or vertically to your taste. The trouble is that it is really difficult to refit properly (there is no reassuring click to let you know that it is in place and solid) and you have no confidence that the transmitter will not just fall off or come loose. I ended up putting the unit in my back pocket for peace of mind but then it is easy to sit on if you forget it's there.
Also, in these days of rechargeable lithium battery technology on cameras, phones and MP3 players, an internal rechargeable battery system for the transmitter would have been a big plus (I can see vast AA battery bills looming on the horizon as I type).
All in all, the Relay "does what it says on the tin" but could be improved in a few areas to make it a really great affordable (especially at Andertons prices!) product. Maybe when they release an updated model they will solve some of these little niggling issues?