I loved FC3. It had a great story, beautiful graphics, an open game world, and handled stealth better than any game I've seen since Thief 2. I enjoyed it immensely. Nevertheless, I stopped playing about 3/4 of the way through. Why?
It was a story mission. You had to swim to an island, kill a bunch of pirates, and enter the headquarters of the pirate leader, Vaas. Vaas sets the building on fire, you have to escape, then fight off all his troops. After defeating them, you have to go into a warehouse where Vaas surprises you and stabs you in the stomach. Then you enter a dream sequence in which you have to shoot a huge number of Vaas clones. If you survive that, you complete the mission.
Only the last part is particularly difficult; everything before that is time-consuming but relatively easy. Unfortunately you can't save before the Vaas fight. If you get frustrated and take a break, you have to go back to the very beginning, swim to the island, clear out the compound and so forth and so on. It requires a big block of time, and prevents you from mastering the one tricky part of the fight through constant repetition.
At least this is an epic battle with one of the game's big villains, and for most of it you're playing the game, not watching cut scenes. It was better than the mission that drove me to quit Saints Row IV. You had to travel to the quest site, go through a series of cut scenes and quick-time events, survive a ridiculously easy battle and then go stunt-flying through trap doors, for which you were given no opportunity to practice. If I could've saved my game before the stunt-flying I might have completed the mission, but that wasn't an option. I felt terrible quitting Saints Row IV one-third of the way through the game, but I wasn't enjoying myself anymore.
So I ask game designers: Please let players save anywhere, or at the very least have a save point for each scene in the mission, particularly if you're introducing new game play.