As many have already said, this is probably the best tactical shooter of all time. SWAT 4 is truly one of the only fps games where you really have to think before you act. While twitch reflexes will get you some way through the game, exercising tactical thinking by appropriately applying your available tools to the situation is absolutely required to win. Every room demands your full attention to detail and analysis as it only takes one bad guy to wipe your entire squad. The random placement of enemies each time a level is loaded prevents you from brute forcing your way through levels through memorization and you are required to think through the situations in each level all over again every time you play. The amount of command you have over your AI squadmates is unlike anything I've seen and really allows you to think about how to approach a situation from different angles and the different maneuvers you can execute.

The shooting and movement are clunky, though I consider this a conscious design choice as the game is a tactical strategy game first and an fps second. Most of the time, if you've applied the best tactics to your situation, your AI squadmates will neutralize all the threats without you having to fire a single shot.

The overall aesthetics of the game are slightly dated but the environments have a high level of variety so you won't find yourself staring at one for too long. The attention to detail to the props found in each level is noticeable and goes a long way to making the environments seem realistic and lived in.

The sound design is extremely well done and is probably responsible for 70% of the immersion factor. The dynamic music that intensifies when breaching rooms is also a great.

Overall, SWAT 4 is a flawless game. Highly recommend it to players who are fans of tactical fps games or strategy games in general.