I have not seen much about people having issues with the web adaptor, but we seems to always have issues with it failing. We have had these issues since 10.1, but it has been a major issue since upgrading to 10.2.2 and moving to a single site with multiple machines. A few of the issues we have seen is the REST unavailable through the web adaptor, but not going to the site through 6080. And getting 404 errors on some of our cached tiles, but only through the web adaptor. Any one else have similar issues? Are there any suggestions for bypassing the web adaptor all together?
This is using Windows Server 2008 R2 and VMware. We have two web servers load balanced through F5 and two app servers with ArcGIS Server, both have 24gb of RAM. We have about 40 to 50 map services.