Most Bangkok cinemas are world-class - crystal clear viewing, digital sound and very comfortable seating. Compare ticket prices with those back home you'll probably want to get in as many films in as possible before you leave! A ticket for a current Hollywood blockbuster at a leading Bangkok cinema costs around 150 Baht (around $3.50), while the same at a provincial cinema often costs considerably less. In New York it will cost at least $10 and in the West End of London it'll set you back around $20.
In addition to regular cinemas, Thailand has its own IMAX cinema (in Bangkok) and its fair share of film festivals and 'art house' film showings. People looking for a regular supply of foreign films often look to the Alliance Française and Goethe Institut in Bangkok to satisfy their craving. All in all, if you are into films, you'll be into Thailand in a big way!