Just a few main characters yes, but sometimes too few can make a book a little claustrophobic.
I think it depends on the book and how the characters are handled.
The hobbit has 14 characters on a journey, Bilbo, Gandalf and 12 dwarves plus lotsa characters on the way. Its not too confusing because you can bundle all the dwarves together, and all the charcters they meet on the way are very minor and only in it for a short time.
I did lose track of some of the minor characters in the picture of dorian gray though, all the ladies and gentlemen at the dinner parties.