Personally I like the rank system they have right now. You dont have to bash on me for that, its just my personal opinion. But i do miss how halo 3 did it to where you had your number rank and your overall rank and your rank in that playlist. I would love to see that come back.
About the joining in the middle of the game, I like it and dislike it. I think they need to add a thing to where it kicks inactive people after so long because i see alot of people just joining and standing there doing nothing. I love the multiplayer tho, i think 343 did a good job with it. Just take out the XP cap and it will be golden.