Mouse Input Is Governed Entirely By Frame Rate
If you play with mouse & keyboard and you raise the frame rate, you might notice how your view slides all over the place at very weird times. This is because mouse input is DIRECTLY AFFECTED BY FRAME RATE. The higher your frame rate, the slower you'll look. The lower your frame rate (until you go below 30) the faster you'll look.
I've made a short video demonstrating what I mean. Think of it like your sensitivity changing on the fly based on your frame rate. It's not literally happening but it might as well be. As I look down the Normandy, the frame rate dips to about 80 fps. In that moment, my "sensitivity" gets faster until I look away and raise my frame rate back into the 200+ range. From what I can gather, this happens in ALL games but is most prominent in ME1. I can't test ME3 since I haven't gotten there yet, but based on the previous games I'd say it's a similar story. Controller input isn't dictated by frame rate so clearly BioWare knew it was an issue and fixed it there.
Mouse dampening might be bad, but this is so much worse than anyone could have possibly imagined. If you play on mouse & keyboard, then I implore you to cap your fps to 60. It's not a perfect solution since you'll run into the same issue if your fps dips below 60; and you miss out on the visual eye candy that is an uncapped frame rate, but it's the best solution you have if you want to be accurate.
On some unrelated business, I found some other oddities with mouse input: In ME1 if you sprint on a controller and switch to mouse & keyboard, you will be unable to turn the camera while sprinting with the mouse until you restart the game. It's not an issue if you stick to one input, but it's just something I found interesting.
Also I'm saddened to report this, but the scroll wheel still has no effect in Mass Effect 2. It works for the settings menus but not for your private terminal and the upgrade station. I really wish it was implemented there. Grabbing the slider is annoying, and yes I know W and S can control certain parts of those menus.
