Loaded question, and you will get tons of different answers. Here is my 2 cents:
CCM is bugged, i mean its like a roach infestation. Here is what i gathered so far:
-Depth Chart issues EX: the cpu will switch the LT and RT simply because the LT is higher ovr and vise versa.
- You cant save your scheme changes in the Coach side of CCM
- Duplicate jersey numbers can happen when you trade someone to your team that already has a dedicated number.
- CPU will run A LOT. I stopped playing after 5 games as this became annoying. They would run 6-7 times in a row.
-SIM stats are terrible. If you have 15 minute quarters i have seen a RB run for over 500 yards in a single game.
Those are just a few issues with CCM and those are what have caused me to neglect getting it till a patch comes out. Keep in mind if you have access to the internet, online CCM i read has a few of these issues already fixed.
If you prefer just "play now" then you are golden, the game feels great and provides me with a great challange. I however am a "franchise" guy and dont really have a dedicated internet connection as i use my phone as a wifi adapter. I simply cant keep my phone screen on for 6-7 hours