We don't live in a terribly cold climate, so I really don't know about helping your heating bill (although my sis-in-law swore by them in WI).
However, we wrapped our one drafty window for a couple years before we replaced it, and it really helped that room. Before wrapping, on windy days we'd see the drapes move. After wrapping, we'd see the plastic "breathe" (swell and relax). But no breeze in the room.
We had wood trim, and could easily get a good seal with the included tape. The hair dryer tightened it so it wasn't particularly noticeable.
Can you get one locally (big box and hardware stores carry them around here). See if your trim allows you to get a good seal before buying a bunch.