I use the plan when we travel in our RV. We are snowbirding and have enjoyed the speed, ease of use, plan coverage, 20gig cap and reasonable monthly charge.
In reading the linked thread the problem sites seem to be limited and many have been corrected but it still lingers. For me all important sites (banking,email,news links etc.) work fine. This is the first site with a problem and believe me when I say we are master web surfers.
Apparently many use the device and never know about the problem. I would have just assumed the site was down but I really wanted to see if I could resolve an issue with my Winegard Carryout satellite receiver so I pursued it.
In short it is a rather limited problem... but a few sites just don't work on 4 and 3g with the Jetpack.