Hmm, seems to be multiple here and on reddit who used miles to upgrade (I just used cash since 0.01 redemption so not worth it)

I think the most interesting thing will be how well J+ sells. I suspect that it will do quite well the first month, as many frequent flyers (including myself) are willing to pay the upgrade fee to 'test it out'. Personally, if I don't think it's worth it (traveling with someone who is in J on the same route), then I'll probably never pay the additional $500 to upgrade again - I think United needs to make sure that all it's ducks are in a row for the launch because I suspect many fellow FTers have the same opinion.