fins are one of those items that are very personal like a mask, you have to find a particular one that suits you. some people will swear by jet fins saying they are the best you can buy, or split fins or force fins or whatever...
force fins seem to get a bad rap on this board for a few reasons
1. they look funny, and some people would never swim around with funny looking fins on their feet.
2. they require a different style kick to make full use of their potential, a standard kick like with longer stiffer fins doesn't make use of the snap action that is part of the power delivery.
3. people judge equipment here based on hearsay and looks.
4. most divers who bash force fins have never strapped on a set, and some of the few who do try them, do so without proper instruction on the different style of kick. So they just swim around kicking like hell and not getting anywhere better then if they used regular fins.
if you are interested in buying force fins, seek out someone who has them, uses them on a regular basis, and knows what style of kick is proper with force fins. then beg them to let you try them with a little teaching on how to kick. the force fin website also has a few little video clips that show them in action. watch the clips and look at the bent knee kick they use in the video.
and as Obi wan kenobi said "use the Force (fin)"