I'm going to tell you I own the WELL R4 MP7 and I am extremely pleased with its performance and build.
when I first purchased it I had one issue with the magazine release breaking. I simply purchased a replacement for 5 bucks and I've used my MP7 in a variety of situations ranging from CQB/MOUT to field operations when my SAW stopped shooting. It is my primary back up weapon when I'm using my SAW.
Its a light compact weapon. Good rate of fire, long lasting battery life. build is pretty good for the cost. you can get extended magazines for it as well.
Dont go off the name when it comes to a weapon. Every one will tell you WELL arent good. Well just like every other gun system out there no matter the company some builds are good some are bad. ECHO1 has its bad and good builds just the same as Classic Army and Tokyo Mauri.