Halo might be a bit overhyped even for its own time, but while it might not blow your mind it's still a good experience
Let's start with the good, Halo's story is quite interesting for a FPS, it starts off a bit slowly but picks off when you progress in the game. The first time around I quit playing Halo before it really got good but decided to give it a second chance, and I'm glad I did. Tho the story isn't that extraordinary compared to some RPGs or space sims, but it still beats those seen in majority of first person shooters and provides for a great excuse for causing some mayhem. You'll be using many different vehicles from tanks to hovercraft, and a wide array of weapons from futuristic alien energy weapons to more traditional human pistols and shotguns.
Combat is also mostly the way it should be, it's a bit strange that in Halo all the weapons are so effective, I'm not sure if I like it or not, but it does mean that you can use variety of weapons throughout the game without hindering your progress. Enemy AI is very good for a game this old, the enemies duck and take cover, and throw grenades which makes the combat quite enjoyable even on the lower difficulties. And the AI team-mates also do their job by getting on the gunner position in the vehicles etc.
The combat isn't perfect tho, the crosshair is the size of a small house and the enemies come in the same formations time after time, but at least they don't seem to be respawning or cheating in any other way. Also some physics are a bit poor, maybe it's just the low gravity in the Halo ring, but when jumping it feels like the Master Chief is floating in the air, and the Warthog(one of the vehicles) seems like it's sliding on ice all the time.
My biggest complaints come from the poor level design and the enemies. In the very beginning of the game I was a bit dissapointed by some of the the aliens; they look, sound, and behave like....Pokemon! It just hurt the atmosphere when the supersoldier of the future is saving the humanity ..from Pokemon... Well I got over this since I don't like Pokemon so it's relatively satisfying to get the chance to blast them in the face with a shotgun. Other enemies early in the game are pretty colorful too and thus not very intimidating. And then the level design... Even tho you'll be fighting enemies from Alien ships to outdoors and buildings, some of the levels were just cheaply made by copy pasting the same room over and over again. For e.g. The Library level you'll follow your guide through a level in this large building enemies swarming from everywhere, it's all very hectic and entertaining, but then you come to a big door and your ”guide” tells you that this is the first of 10 doors... And yes indeed, you will basically repeat the same level 10 times while the same enemies come from the same predictable places with the same predictable tactics. And it's not the only level using copy paste design, this is even more annoying since the game is relatively short, I passed the SP campaign in less than 10 hours, and lots of this time was spend in the copy paste levels. And when the levels aren't very detailed, mostly just grey or brown hallways with poor textures, there's a big chance you'll get bored before finishing the game.
Despite the problems I can recommend this game to most players, the combat holds up to current shooters, you can quickly toss grenades and hit enemies with your weapon, AI is good and as such creates some very exciting moments. Add a solid story and you've got a good game wort playing.