Just got back from driving it, since I live all of two miles away.
Hit the road eastbound around 4:30pm; there were a decent number of vehicles on the road, but not enough to slow anything down. I do wonder why the speed limit is only 55 instead of 65; that said, drivers seemed to be taking it a little slower on the ICC than I generally see on most DC-area freeways.
Exit 9 (MD 97) eastbound, I can tell, is going to be a problem for drivers still getting used to the road. The combination of signage and lane markings seemed to be confusing to the driver in front of me attempting to reach MD 97 NB (exit 9B), as he first got into the proper exit lane, then changed lanes back onto the mainline shortly before the exit, then ultimately had to cross the gore to make the exit.
The temporary westbound beginning at MD 28 features what might be the largest reassurance shield I've ever seen.
The transition between I-370 and MD 200 is seamless, especially westbound. Both I-370 and MD 200 now feature 1/10-mile markers over the whole route. These mile markers do not reset at the route number change, which occurs around MM 2.4, IIRC.