I think it goes without saying at this point that the game is a great technical and artistic achievement. It looks great, the audio is great, it has lots of interesting little features, and the prison camp that is the setting for Ground Zeroes is an interesting and varied place to sneak around - not that I actually spent that much time sneaking. It's really a personal failing, rather than the fault of the game, but the sheer size of the level and uncertainty about how the saving system works combine to put me into a kind of fatalistic state where when I get spotted I don't care about stealth any more, I just want to finish the mission and move on. Certainly on normal mode it's easy enough to just mow down the marine patrols you run into; they're no threat to you (unless you maybe get caught in the open surrounded by three 4 man teams or something, but you'd have to be pretty dumb to end up in that situation). It helps that they leave unlocked AFVs lying around, and the crewed ones get easily confused by cover, or you can just sprint past them. Plus, the main entrance seems a little loosely protected?
I'll admit I'm not sure if I'm going to continue playing the whole thing. There have been some boss battles that were okay without being amazing, and while it does a decent job of mixing things up with your tasks and the battlefields, some of the combat can feel a bit samey. I'm still glad to have revisited it though, and writing this and looking at the screenshots I took does make me want to load it up again at least once more.