I cannot find any real documentation on the ExecutionLogLevel setting in SSRS 2012 (which is expected to be the same as it was in SSRS 2008). What changes when you set the setting to "Verbose"? Do you get more data in the same amount of rows? Do you get more rows? Both?
One thing I'd like to know is if by using "Verbose" would it make it so I don't have to consult the (lame) SSRS LogFile directory when things go wrong? (Seriously: Worst. Log. Files. Ever.)