Window films - worth it?

[SVS]

Any opinions whether window films are worth it?

Do they genuinely reduce UV and keep rooms cooler in summer? Can any films keep a room warmer in winter?

How about extra security against your window being smashed? Does this require removal of beading to fit properly?

Cost?

[Zetec-S]

We had some fitted at my old company a few years ago because someone kept complaining about the glare when the sun shone through

All it achieved was to make the room a bit darker so we had the lights on more, didn't notice any difference in temperature.