jimnms: I don't want to post ay spoilers, but I'm in a part I remember. I managed to make it through the first time, but forgot a little thing and got killed. The checkpoint started me way back, and now I can't seem to make it. I tried for 20 minutes to get through it before I had to quit. I was getting so mad I wanted to punch something. I had to stop myself from slamming my fist on the keyboard or punching the monitor, and I probably woke up the neighbors yelling at the damn game.
Yeah, the checkpointing in the middle of the game is a bit weird. It's an interesting section because it's very nonlinear, in that there are several different directions to go and a bunch of things that all need to be done before you can proceed. The problem is that in order to make sure nothing gets broken and the player doesn't get irrevocably stuck, the checkpoint needs to be pretty far back. I think it's also compounded by the level of tech at the time.... a modern computer could probably keep track of all the variables in a more robust checkpointing system but on the Amiga this was not possible.
Overall the game has a lot of trial and error, which was one way to extend the game length and also slow the game's pacing to a point that works much better. Today, I can finish the whole game in about 20 minutes and it loses a lot of its potency when rushed through so fast; back in the day each screen was an achievement and the game felt like a much more meaningful journey.
The downside, of course, is a lot of frustration, as you've found. I would argue that the game is more interesting in a historical sense than it is objectively good.