I reverted back to iTunes 10.7 also.
Apparently no one at Apple no longer uses a computer.
They seem to only use an iPhone or iPad.
First they removed Front Row for all of us that used a large TV for an entertainment center and now "Full Screen" Cover Flow.
I am attaching a photo below to show all the people at Apple what an entertainment center looks like when using Full Screen Cover Flow on a 55" Sony HD TV.
Myself, like many other here, spent days, weeks, and/or months, collecting Album Art covers. The new iTunes is horrible showing small Album Art covers. That is pathetic.
Try doing the below with the new iTunes 11

To say I am unhappy with them removing Cover Flow would be an understatement.
I will be staying on 10.7 as long as I can or until they bring back cover flow for iTunes 11.
And yes, I get the -42408 error but can live with that much better then I can live with iTunes 11.