I really don't know nor understand why Batman Begins has got so many poor reviews from critics. True, the Elfmanesque main theme isn't there and the musical material is very dark and sometimes dissonant but this is a whole new Batman-film and franchise. In my opinion Hans Zimmer and James Newton Howard have done very good job here. Batman Begins is a very beautiful and powerful symphonic tribute for the dark knight. Zimmer has accomplished the more muscular superhero material while Howard adds the gentler touch and humane side to the score; both musical elements complete each other and form a wholeness that reflects the Batman-character wonderfully. In addition I like very much the idea of name each track after the latin term of different bat-species; it's quite unique an idea and the names sound very impressive.
All in all I can't but love the score of Batman Begins. It somehow grows every listening. I consider Elfman's Batman Returns the best Bat-score of all times (it is simply very underrated, ingenious, operatic and beautifully melancholic score) but this comes very close in terms of beauty, power and passion that belong to this particular world of the newly resurrected superhero.
Batman Begins is one of the most individual and strongest works of Zimmer and Howard. Just listen to it more than twice and give it a chance!