Image quality results have been added to the Canon EF 24-105mm f/3.5-5.6 IS STM Lens Review page.
If you are like me, the 24-105mm STM vs. L lens comparison is the one you are most interested in. I'll let you draw your own conclusions.
B&H has the Canon EF 24-105mm f/3.5-5.6 IS STM Lens in stock.