Gave it a shot, and it worked out
I wasn't sure about these things so I just bought the cheapest one I could find even though it had very low ratings. Couple days later, and I've got dramatically cleaner windows. The magnets are strong and could smash your fingers if you're not careful, but following the instructions makes the easy enough to avoid. There are $40 options that may be better, but this worked well enough.
Rating: 4 stars