P1na: BTW, probably because of the 100+ hours I've put on both VC2 and VC3, when replaying VC1 I gave up pretty fast. It was just way too easy to be interesting. I guess I'll keep slowly playing it, but I don't really have much of an interest on playing that right now.
I think the difficulty of the game is just right (for me anyway) when you play it for the first time. But it often relies on surprise, and it is VERY easy to exploit when you replay it, or if you savescum.
I immensely enjoyed the game, because I ignored the rankings and avoided all exploity things (like reloading or restarting after a nasty surprise, scoutrushing and the like). But now, I don't think I would really enjoy replaying it, since the surprise is gone and I know how to cheese many levels.
Typical example : The battle with the 2 mortar tanks that counterattack after you take an enemy base. I did it on the first try, and it was a 12 turns long difficult battle where I had to adapt to a situation I was completely unprepared for, had to evacuate half a dozen wounded, and where Rosie heroically held the southern trench and shot down maybe 30 imperials with her defensive fire while most of my army was trying to get to the northern tank or to defend the camp against the snipers. I got a miserable D-rank, and it was awesome. But now? I know I could cheese it on turn 3 or 4. I could avoid exploiting what I know, sure, but the magic is gone, so I don't think I'd enjoy replaying it.
So the replayability is weak, unless you are chasing for the integrated medals/achievements. But the first playthrough was 30-40 hours of pure awesomeness. And I still have the DLCs to play (although I will probably enjoy them less, since they're lighter in "story" content. But the tactical "first time" challenge will be there)