Halo 5 is sometimes disappointing, but it still exceeded my expectations because I had literally no faith in 343.
I did not like anything from Halo 4. I tried to get into it multiple times coming back after weapon tuning and DLC because I bought the collector's edition. I had no trouble doing well because I used all the overpowered setups before they were popular: Thruster pack, ammo, mobility. I pretty much was on cycle in that game with constant power weapons so my k/d was actually higher than past games. However, I felt the game required no skill, wasn't Halo, and had COD elements added without tuning and implemented poorly. It's honestly the worst multiplayer I've ever played. It reminded me more of Section 8: Prejudice than a AAA title. All the maps were complete garbage and boring.
I also hated the graphics of Halo 4 and don't get the appeal to it at all. I also found a ridiculous amount of bugs in the game especially related to the AI which made the game on legendary super easy. I beat it blind in 5 hours on my first playthrough on legendary and it wasn't challenging at any point. I thought the story was completely out of place with the series and the soundtrack didn't feel right. They couldn't get theater or fileshare right for months. There were little tiny changes everywhere that all added up to making the experience worse. They went out of their way to change things for no reason such as being able to move when you pause for the scoreboard. Multiply that by a 100 and you get my point. I was on full board with the "Halo is dad" train after Halo 4. Halo 4 was the worst AAA game I ever played. Halo is one of my favorite gaming series and I don't say that simply due to expectations. I just thought it was a bad video game. If it wasn't Halo I wouldn't have bought it.
Then we had MCC which had its own list of issues. So at this point I did not expect much from Halo 5. I bought it mostly just to see if 343 could make a good campaign. Once again I was let down here.
However, after playing a lot of Halo 5 I have mostly positive feelings about the gameplay. Halo 5 is a fun game with decent mechanics that takes more good than bad from Call of Duty and fixes a lot of stupid things Reach and 4 did wrong. I could go a lot more in depth, but basically core gameplay is the best since Halo 3. It doesn't feel like classic Halo, but it feels unique in its own right.
Halo 5 has a lot of problems that are not related to gameplay. No infection, oddball, or king of the hill. There's a lack of good quality maps (still better than Halo 4 maps) and due to one DLC map coming a month it seems like it will be a while before that is fixed. I have a lot of negative things I could say about the REQ system.
I'm not going to nitpick the game to death because right now I enjoy it. 343 redeemed themselves, and I will consider getting Halo 6 at full price. I got Halo 5 for half because of abusing a bing rewards special that was going on a couple weeks prior to release.