Hi!
I have s FF (v 1.x) standard license: the program is well done and powerful, the best thing is the huge user filter library (something like 7000+ filters).
I thought I would have used it more often than what I'm actually doing, but I can say it was worth the (discounted) price I paid. I'd suggest you to deeply test the demo before buying (as usual...), keep in mind that for most users the standard license is enough (you can upgrade to pro later) and that they use to have some huge (40/50% off) discount sales in a year... if you're not in a hurry it's worth to wait for the next one π
if you're looking to FF as a procedural texture maker only (FF has many brilliant image-editor filters too and can be used from within PS or standalone) and you're a Win-only-guy, you may want to try the free MapZone from Allegorithmic: http://www.mapzoneeditor.com/index.php?PAGE=HOME
it's not in development anymore but still a great tool for free...
finally, if you need to create normal/bump/refl/etc. maps from your textures take a look at ShaderMap: http://shadermap.com/ - it's not free but very cheap (20$ for the "pro" GUI version). also win-only but works fine in OSX under VirtualBox
cheers,
Alessandro