I also upgraded my 24-105 to a 24-70 II.
I really miss my 24-105, or rather: its IS. It happens ever so often that I shoot something and I want to close the aperture to f/8 or so, for the DOF needed. In those situations the IS really shines. I could shoot static objects like architecture or flowers at 1/10s without issues, whereas now I need to shoot at 1/100s or so. A huge difference. I took sooooo many photos I really like with the 24-105 in dim light, at dawn or a bit afterwards, and I found IS to be a great asset. The 24-105 IS really shows its best sides during the blue hour. The 24-70 is hopeless (in comparison only!) during that very attractive time of day. Bumping up ISO is not an acceptable option, IMHO. So, I really miss IS but I don't miss the reach.
Having said that, the 24-70 shines when anything moves in the scene. 1 stop of Tv is a huge difference when shooting people in available light, also a very attractive situation. There I usually want to shoot at 1/80s or so, and for this type of work IS doesn't help too much. I can improve so many shots now that would have been motion-blurred a lot more with the 24-105.
In all, I do not wish my 24-105 back. When I set out to do high quality architecture during the blue hour, I compensate for IS with a small tripod. The side effect is, that it also helps composition.
I hope to have been useful, have fun with your new 24-70!!