I raid normals and heroics. Not even close to world 100 (hmm.. I'll just go check WP now - there it is, somewhere in top 4000). And I think that LFR is very good place to practice fight for anyone who not seen it in less stressful situation than real raid. Yes, if you're consistently raiding you're most likely already know it from real raid, but it is perfect place for people catching up to practice.