I read some of the precut sizes don't cover 100% of the headlight so I went universal. My headlights are curved and have some difficult features (07 civic coupe).
I had the benefit of having the headlights already off the car. The 12-mil sheet was nice and thick but flexible enough to be applied in MOST areas - some tight protrusions and tight 90 turns were fairly difficult. The adhesive backing was really tacky so I had to use more water - heat gun definitely helps mold around features and curves. Still, a couple of the features and edges ended up sub-optimal. There were more than a few water/air bubbles - most I was able to get out with the included squeegee card. I'm still waiting for some of it to dissipate.
Film quality is great - nice and thick. Though fairly smooth, the optical quality has a very-slight orange-peel - a little bummer if you've just retrofitted projectors and are looking at the work. Most of it is unnoticeable.