Back in the Olden Days when I was a mere youth, there were plenty of what were called "sword and sandal" movies. Some were pretty good. Some weren't. One that really impressed me at the time was The 300 Spartans. It starred Richard Egan and it was about the same battle at Thermopylae. I was impressed with the story and the heroism of King Leonidas and his 300 men. It's remained a sentimental favorite of mine, so I was prepared not to care much for 300, the jazzy re-telling of the story based on Frank Miller's graphic novel.
Well, imagine my surprise at how much I liked this movie. I know I say all the time that movies look great. This one looks really great. Don't take my word for it. Watch the movie and see for yourself.
You already know the plot. King Leonidas and his 300 Spartans hold off tens of thousands of Persians and die bravely. If you don't like battle scenes, blood, and lots of talk about love, honor, courage, and duty, you might be put off. I think Robert B. Parker's Spenser would enjoy it, though.