I'm fairly sure they've worked out all the guitar issues, but not the drums. I actually RMA'd my guitar and drums on EA's website back on January 14, and I just finally received everything last Thursday. The drums were exactly the same as my old pair (rolls are very bad on the red pad, lots of missed hits), but the guitar is excellent. I could tell it's a refurb (both the drums are guitar were dirty in spots), but the strum bar is much, MUCH improved and star power activation is flawless.
As a side note, I actually fixed my drums while I was waiting for my "new" pair to arrive. There's a fix out there for the QM models that involves placing a piece of tin foil inside the actual pad (near the sensor). I highly suggest looking into the fix for anyone with the QM drums and the roll problem.