The Lord of the Rings movies are among the finest movies ever made, period. The Two Towers is no exception; it is just as epic if not more than its predecessor The Fellowship of the Ring, and has more complicated characters like Gollum and Faramir, both of whom get introduced in this chapter of the saga.
Gollum is by far the show stealer; Andy Serkis did a perfect job showing two sides of the same coin with Gollum and Smeagol, the same character but totally different personalities. Gollum is the ring obsessed creature, while Smeagol cares for "Master", the name he calls Frodo Baggins by. The story could be interpreted as a reflection on how the one ring managed to change Smeagol entirely from a normal breathing person to a deformed monster who only keeps on being preserved by the ring's powers.
I highly recommend The Two Towers for anyone who loves great fantasy movies or epic movies. The film never falters with its pure sense of scale and awe. These movies are wonderful slices of cinema that no fantasy filmgoer should miss.