Film solves a lot, but not every window complaint, and it's worth knowing the limits before you book.
The big one is glare. If harsh glare is bouncing off a neighbor's metal roof or another bright surface outside, interior film won't stop it. Film cuts the sun coming through the glass, not light reflecting off something outside your window. For that kind of glare, an exterior shade or awning does more.
A few other cases aren't a fit either, such as cracked glass or a failed seal, which would require a repair or replacement, not a tinting job. And if you want a quieter room, film reduces heat, glare, and UV, but it doesn't block sound.
When it comes to fading, film is preventive. So, it stops future UV damage but can't undo fading that's already hit your floors or furniture. Once you know what film does and doesn't do, the choice gets simpler.