What I got was a standard Tim Burton semi-scary movie. The imagery is similar to other Burton films ( The Nightmare Before Christmas and Sleepy Hollow). I have grand children and I know that most of them would be frightened by the Burton version of Alice until they reach age of 12. Before that I would expect nightmares.
Read the online original by Lewis Caroll. It is definitely a stoner story as the hippies quickly recognized.
Don't confuse it with the Tim Burton version which mashes together Caroll's Alice with its sequel Through the Looking Glass and turns a stoner story into a 'bad-trip'.