This movie is considered a classic of modern horror and gave us the "fast zombie" movement that took hold in the early 2000s. Danny Boyle is a great director and this movie has much to recommend it but I actually like the sequel more.
For those who don't know, this is about Cillian Murphy waking up after being in a coma and finding that the world has turned to shit due to a "rage virus" that is transmitted through bites and blood. Murphy wandering the deserted streets of London is iconic and haunting, I must admit. He eventually finds other survivors and they make their way out of London and into the countryside where they run into a paramilitary force that has created a "safe zone" holding out the infected.
I feel like the hoariest trope in horror movies is the idea that we are the monsters. What starts as a pretty great zombie survival movie turns into a very different film when the survivors meet up with the military guys who are into raping and being evil. I feel like other movies have made this argument more subtly and with more finesse. The entire third act at the military compound feels very "been there, done that" when we have a whole new mythology to explore. The sequel follows a family whose father becomes infected and seems to always be leading the attack on his children as the movie goes on. The emotional underpinning and family dynamics just make that story stronger than another, men abuse power scenario. Obviously, your mileage may vary.
A must-see of the zombie genre.