Is Invisionfree a good free forum hosting and creating site?

I am want to create a free forum for my online community. I checked out invisionfree, forumotion and freeforum.org. Invisionfree seems like the best one, but I want someone else's opinion besides the company. I googled them and mentions of "down" problems came up. forumotion looks like it may allow annoying pop up ads since it uses annoying pop up ads to advertise itself. freefourm.org looks like it limits the size of your forum so...help! Any better free forum options? Is Invisionfree good or what?