I have a Rockrider 8.2, generally very pleased with it. Used to work for Decathlon Surrey Quays and although I am somewhat biased, I thought the staff on the bikes department were well trained and knowledgeable, (especially in the workshop).
After 4.5+ years I realized (or actually chose to do something about it), that I had been riding round with a slightly off centre frame (rear wheel leaning over slightly). I got Decathlon Reading to have a look and eventually they replaced the frame, for a Rockrider xc (a higher spec bike, frame supposedly identical). Frame still looks slightly wonky to me, but doesn’t really effect it.
All in all good quality peace of kit, not bad after sales back up I recon.