As a big fan of the original, three things always stood out as to why I thought of it so fondly: Its great storytelling device, amazing sound, and its mixture of intense and thrilling moments.
Call of Duty Classic shows WWII through the eyes of three different soldiers -- a Yankee, a Brit and a Russian. The core gameplay is the same (aim down the sight and shoot Nazis), but the atmosphere is distinct in each. You get a real sense of the Allied Forces. That was true when Call of Duty hit stores in 2003 and it's still true today. The sound, which for the time was loud and powerful, feels muted and is altogether unmemorable in the Classic version. Maybe it was a poor mix. It doesn't do the game justice. And those intense moments? Those still exist, though they aren't quite as gripping by today's standards.
Where Call of Duty Classic really stumbles is in the areas that had to be reworked for consoles. The controls, while trying to adhere to the original's layout, are a little frustrating. Swtiching between guns and grenades is handled with the shoulder buttons and is too slow. The original benefitted from keyboard shortcuts to select the proper weapon quickly. And there's no quicksave, forcing you to rely on checkpoints that don't come often enough. Quicksaves are pretty common for console games, so removing this feature is a real head scratcher.
If you want to go back to a more traditional multiplayer offering than Modern Warfare 2, Call of Duty Classic might be worth checking out. You don't have a persistent character and everyone enters the arena on equal footing. There are six modes included, with the best being the survival mode, Behind Enemy Lines. Online play runs smoothly and the kill cam (a revolution when introduced in the original COD) is back and works perfectly. Multiplayer is limited to eight players, a far cry from the 32-player spectacle of the original PC version. And it's a pretty pathetic offering for any console shooter. Even though the modes are good, all of them would be better with 16 players.