My rating is just the average rating for all the games.
Overall, it's great that almost the entire series is in one complete package. Without this, I would've never experienced Halo.

Halo CE: 6/10
Halo 2: 9/10
Halo 3: 8/10
ODST: 7/10
Reach: 10/10
Halo 4: 6/10

*Played as part of the Master Chief Collection

I actually played this game before on my cousin's 360 one night during a sleepover. I didn't really like it and thought the story was interesting but didn't get the hype for Halo as a franchise off this one experience.

Coming back to it now, fresh off the back of the rest of the MCC, and particularly Reach, I don't think my thoughts have changed much, to be honest. The story is interesting, particularly Cortana's rampancy (also they made her hella sexy for some reason? Like during the 4 year time gap in the story she just developed a gyatt?) and you can see that 343 is setting up a new storyline for the franchise, which is the most interesting part of the game for someone who is newly invested in the Halo lore like I am. The downside is that everything else in the game is just kinda mid.
The new enemy designs (and redesigns of the old enemies) are just lacking and for the redesigns, downright ugly. The gunplay doesn't feel as good or as visceral as it used to. Headshotting enemies in the previous games (or popping a grunt's little backpack thing) used to be so much fun, but now it all feels kinda limp. I can't even explain it properly, it's like a mixture of the guns not having enough oomph, and the enemy's dying animations being lacklustre.
Even the introduction of a dedicated sprint doesn't do enough to make the game feel fun to play. The level design is also noticeably worse, especially in the back half of the game.

It's a very mixed-bag experience overall, but I am tentatively interested in checking out where this story goes from here.
I'm kinda torn if I should wait around for an announcement of 5 coming to PC, or just check out Infinite? Would appreciate some suggestions from fans of the franchise.