Save file length: 44h4m (although it's a bit over 50 hrs when you add in all the deaths that don't count toward it), 93% Complete (didn't use a walkthrough).
I was enjoying it until the final area when a lot of it became flip a switch, take portal, cross to the other side of the room, take portal, flip switch, take portal, take 5 steps, take portal, etc. That wouldn't have been so bad if the Portal animation wasn't about 15 sec. while it's loading the area.
The bosses were more annoying than difficult. The true end boss (not the literal end boss) was the only one that was a real challenge. For a couple of them, you could just hide behind the indestructible Light Crystal poles (why didn't the Luminoth just create mobile cages/armor out of them and destroy the Ing?) and whittle the boss down with practically no threat of dying (especially since you're regaining health while hiding behind the pole). I really found the one where it's vulnerable every 3 min or so (as far as I could tell, you couldn't make it vulnerable, you just had to dodge it for about 3 min) extremely annoying when trying to figure out the strategy yourself since NOTHING that you actively try works.
I really didn't like the Light/Dark Ammo convention. I also didn't like the whole Dark Aether damaging you since it was basically a minor annoyance the vast majority of the time (there were several times where I would just head to a beacon and just stand there watching my health regen for several minutes (I did laundry during one of those times, or did some griddlers/picross)). Because of the gradual damage, the delay of up to about 6 seconds before a door opens is ridiculous (grocery stores have better motion detectors), especially when I actually died after the first boss fight in the Dark World waiting for the door to open. Also on the subject of the bosses, several of the Save locations were extremely annoying since many of the ones before the boss fight became inaccessible directly following the fight making you have to hunt down a new Save Station.
