My first upgrade was a total bomb. The R12 portion went OK, only three minor problems that I corrected as the patching was taking place. Took about three days, but it finished with about 40 or so objects invalid (which I consider pretty good considering the umpteen thousand that are in the database).
Instead of just going with the 12.0.0, I decided to apply the RUP3. Might as well be up-to-date when you upgrade, right? While applying the RUP3 patch, it filled up my filesystem. I started deleteing some logfiles so I could continue, but couldn't keep up with adpatch. It left my db in a state of total chaos. Did I mention I didn't backup after my R12.0.0 upgrade was complete?
I noticed that during the R12.0.0 that I was using a decent amount of CPU on the middle-tier and my db tier was busy but not pegged. I swapped out my Solaris middle-tier for an X86_64 middle-tier to see if that speeds up the process.
One thing that came up during the initial install was adrunias.sh was trying to start Java from /tmp/RapidInstall/jre/Linux. The rapidwiz kept throwing an error of RW-50010 which was totally non-descript. I finally ran adrunias.sh with ksh -v to see what it was really doing and found it was looking for the jre in /tmp/RapidInstall/jre/Linux but the only directory was /tmp/RapidInstall/jre/Linux_x64. A soft link cured that problem and I am continuing on my way. Lets see where this takes us...