I'd say coverage has been good-not-great. Maybe great relative to usual track coverage, but not in general.
I often listen to the NBC/ESPN coverage of the major tennis events during the day at work, and I still don't think the voice talent they have doing track is in the same category as that group. They can be informative and relatively non-annoying for HOURS. They all tend to know a lot about the top 25 international players, and almost all of the US players in the tournament. History, recent results, training information, differences of individuals on different surfaces, etc. They're usually really good at interacting with the athletes and their coaches, working in the human interest stories, and fitting their own experiences into the broadcast when relevant.
I still don't feel like this T+F coverage is close to that, and it should be easier to be tack-sharp for a couple of hours for a few days than 6+ hours for two weeks straight.
Perhaps it's a culture thing. Maybe athletes their competitive days don't have the ability to transition to broadcasting as easily. Are they all pretty much laser-focused on their own events? Are there any 10k runners that also care about the javelin, just because it's part of the sport they enjoy? With football, a QB still needs to know a lot about all the other positions when they're playing, so they can speak pretty intelligently about then in the booth. Maybe there really are just so few people out there that are actually students of the sport (like many top HS and college coaches), and follow the competitive circuit really closely that this really is what we're stuck with.
It seems like there would be some incentive for the Nike/USATF machine to go out of their way to foster growth in that area, and then just say to NBC, "hey, here's someone that's personable, knowledgable, and it's Tom Hammond!" With things like tennis or golf, or even like the the USA Diving trials that have been on, most people can turn those on for an hour or two and get a lot out of the sport. With track, for me, everything kind of feels like marketing. I didn't have to see ads urging me to sign up for a diving membership, or outreach programs. It was just diving. I feel like in a month I can watch the olympics and have some sense of what's going on with the people involved. I don't think that happens as well with T+F.
That being said, I still think there are serious production issues with the coverage that are a major hinderance to gaining wider adoption, and even with better people in front of the camera, that's a problem that will need to be overcome at some point.