I've been hooked on DIII since around January, and hopefully it's starting to wear off because, let's face it, we've all got shit to do and that is one addicting game.
Let me say this: I like the save system, which is actually NO save system. If I'm playing Civ, and I suffer a setback, I do indeed tend to reload. That's not good. That's just making me WEAK! But DIII teaches me to be strong, like BULL! When my prophet dies, what are my choices? Start a new game, or tough it out! I can appoint a new one in a few turns anyway. Lose a province, lose an arch-devil or queen of elemental air? Recapture, re-summon! Fall back and regroup.
I haven't touched the MP aspect, which of course also keeps me weaker, but at least with the no save system you learn to overcome obstacles instead of reloading them out of existence.
This is not high praise for the game, but some of the reason that you can survive the occasional crushing setback is that the AI is not so good at pressing its advantage. It can certainly take you down on impossible (note that the AI gets double money and resources at that level, which explains it), but in general you can live to fight another day. In a game like Civ, IIRC, the AI is less forgiving.
Although, it's also worth pointing out (unless I'm wrong) that there's no AI alliance system in DIII, so the AIs are always busy watching their backs and have trouble concentrating on the real menace of your SP empire. So maybe the Civ AIs just have it easier.
What-EVER. Point is, it's a great game. And scripting is the key to battles, and really needs to be tailored to situations to get the most out of it. Sometimes I wish it really WAS just a matter of dciding where the troops set up; because SP turns can start to take 30+ minutes if you start getting obsessive...