I doubt that someone could learn higher category theory (and more in general higher dimensional algebra) without first studying a little of category theory, mostly because the definition given in such context use a lot of category theoretic machinery.
About the textbook reference: MacLane's "Category theory for working mathematicians" may be a little outdated but I think it is still the of the most complete book of basic category theory second to the Borceux's books. Anyway there isn't a best book to learn basic category theory, any person could find a book better than another one, so I suggest you to take a look a some of these books, then choose which one is the best for you:

S. MacLane: Category theory for working mathematicians (I've already said a lot about this)

S. Awodey: Category theory (Peculiar because it has very low prerequisites and it's rich of examples too) 

J. Adamek,H. Herrlich, G. Strecker: Abstract and concrete category theory (freely avaible at at this site "http://katmat.math.uni-bremen.de/acc/acc.pdf", maybe the book with the greatest number of examples from topology and algebra)

After you have read one of these book, you could also use Borceux's books and read some more advanced chapter of category theory which aren't discussed in the previous books.

F. Borceux: Handbook of Categorical Algebra 1: Basic Category Theory

F. Borceux: Handbook of Categorical Algebra 2: Categories and Structures

F. Borceux: Handbook of Categorical Algebra 3: Categories of Sheaves

For higher category theory I know just few reference: 

Leinster's "Higher Operads Higher Categories" (http://arxiv.org/abs/math/0305049), 

and 

Lurie's "Higher Topos Theory" (http://arxiv.org/abs/math/0608040) 

other good reference in higher category theory and higher dimensional algebra in general are Baez'[This week's finds][1] and [arxiv articles Higher dimensional algebra*][2].

Hope this may help.


  [1]: http://math.ucr.edu/home/baez/TWF.html
  [2]: http://arxiv.org/find/all/1/AND+au%3A+Baez_John+ti%3A+AND+algebra+AND+Higher+dimensional/0/1/0/all/0/1