Depends who you are playing with but if everyone has stable 200 ping which is for me everything but south america and australia then its definetely fine. I would say that lag is comparable to me playing on the korean server on DE
A noob is a beginner and everyone that is as bad or worse than a beginner. So I would say 1000-1200 elo and lower.
The real questions are tho: What is a semi noob, ultra noob, real noob, mega noob, noobish, good noob or no elo noob.
DE also doesnt have mods. So people just randomly ragequit, dodge ladder games, troll and nobody cares. 1v1 or games with people that you know are all thats enjoyable there. I prefer voobly for teamgames still even if there arent as many players anymore.