Never ever had any trouble when droping DS off at nursery. He started there at age 2, he was then non-verbal with very little understanding of words. But he was bowled over by the huge train track table and all the differents vehicles they have there. I suspect that is the real attraction for him!
Up until very recently, he'd go in and instantly forget about me (i'd always have to go to him for a kiss goodbye).
He just love it there, during the summer break and weekends we now hear "going nursery afternoon mummy!".
DS did play alone for a long, long time...but he still enjoyed himself.
Now he tends to parallel play with the others and can interact with peers but on his own terms.
What amazes me is the fact that my older nt ds (now 16y) didn't like nursery much, and grizzled a fair bit whenever he went there.