I have used their parts in about 5 builds now. They have the lowest price around, but quality is spotty enough that I won't be using their stuff any more. Aero and PSA parts are just barely more, but quality is much better.
Of my Anderson builds, I've had two uppers with out-of-square faces, so that free float handguards sit crooked enough that gas blocks almost touch the inside of the handguard, one out-of-spec bolt catch, and every Anderson upper I have doesn't line up well with other brand lowers... pins barely go in. Also every LPK has extremely stuff detents on takedown pins and safety. Makes for a hard-to-manipulate safety that is very noisy when it does go. Also their lowers don't have the pistol grip installation hole threaded all the way, and require a shorter bolt, which can be a PITA. Enough little issues like this make the low price just not quite worth it.