bengeddes: The two most objectionable parts I am responsible for (changed GUI and custom items added to the drop pool), so I'd be remiss not to mention that you can reverse both of these changes and still enjoy all the fixes from the CM Patch.
Yes, you can pick if you want to use those 2 or not and that is how it should be. But there is a ton of stuff which you have no control of. I did some extensive testing with it a few years back (CM Patch 1.60) and I landed on a decision that it changes too much for my taste. Still have my notes on it that I made during the testing.
Like the changes to how certain skills work. Seraphim Pelting Strikes with ranged weapon firing 5 shots instead of 2, making it hideously overpowered and making it pointless to use anything else? Same with Frenzied Rampage on Shadow Warrior and ranged weapons. I stopped playing once I found out that I've been doing 150% more damage than intended with my BFG Seraphim because of the patch and me using Pelting Strikes.
Then there is the Hurl modification change on Scything Sweep which made it significantly harder to kill enemies with the corpses. Tested it and the difference is huge.
Or when it comes to enemies, some of them lost knockback because there apparently is a small chance of a bug occuring where the player loses control of their character. But removing it entirely is not a good solution for me.
There are also balancing changes to enemies. These should absolutely be optional or there should at least be a guide on how to manually revert the changes if you don't want any balancing changes.
Then there are the animation changes. The transition animations (like when you start/stop moving, start/stop shooting a ranged weapon etc.) have been sped up so much they are no longer visible. Yes, doing it prevents some animation issues but it was a unique thing that I liked about the game.
Or how the quests are handled in the patch. Fixing original quest bugs? Awesome. Introducing new quests/unfinished(restored) quests? Questionable. People who never played the game before probably won't care, but some people might want to play just the Sacred 2 they remember without any extra fluff.
Same with the epic mounts mod integration. Some might prefer to play without it.
Or even minor things like the ship ports and baloons working just like teleports. A convenience change but it reduces immersion. Or the new NPCs which work as portals in secluded areas. Another convenience change but it was fun having to venture from a hub to a secluded area. It had this "expedition" feeling to it.
Or mounts being summonable in dungeons. Another convenience change but it made sense that they were afraid of going underground. Running around on a horse in a cramped cave also looks silly.
Even little things like boss battle zoom out. Yes, camera is in player's control but some bosses are so big that you have no way of seeing them in their full glory.
Or the removed physics effects (swirling leaves etc.) that you have to restore manually after installing the patch.
The patch does a ton of great stuff like fixing the memory issue, numerous bugs etc. I am not discrediting the huge amount of work that went into it. It is a great effort, but all the additional/changed stuff that impacts gameplay in any way should be optional and not forced upon the player.