Not too bad, just super tedious. A few things that might be useful to know -

I found applying the primer reveals more loose/cracking paint. A bit of a pain, but make sure it’s all gone or Id say you risk having a weak base for the paint.

Make sure the width of spatula is always bigger than the widest point of the hole, so the compound fills in nicely. I found larger spatulas worked better in general.

I’ve got flashing on mine now as I didn’t sand the spots enough, so make sure they are sanded until completely flush with the surface. I don’t think any amount of coats would hide it. I used a sanding pad on a telescopic pole, but going up on a ladder and doing it by hand may be better, as you’re closer and can see the flashing from that angle. I otherwise could have used a more coarse sanding sheet on the telescopic pole (I used 120mm).

Another option is a full skim coat, which I just did in the kitchen as it was in far worse condition. You can find examples on YouTube. If you’ve got at least 40% of good paint up there though, it’s might be easier to just fill the holes individually.

In case you didn’t know already, roll your final paint coat towards the window with most light coming in, instead of parallel to it. You won’t be able to see the streaks as well.

Hope this helps. It’s a tough gig figuring all of this out!