I cannot answer if it is worth it or not for you. It has been about 7 years since I've been to Yellowstone but I seriously doubt if it has changed significantly. Here are my thoughts.
1) It is going to be crowded. Just take it in stride. No need to get upset or rushed. Get used to the feeling of "go with the flow". In some ways it is not as bad as some make out and in some ways it's worse but it's all part of the "Yellowstone Experience."
2) There will be tourists (and idiots) doing stupid stuff like getting too close to the bison and, heaven help them, moose. It happens. Get the video settings on your camera right. You may become a YouTube Viral Video Celebrity if you capture the right action at the right moment.
3) Wildlife there is like wildlife anywhere else. Some times they are out and about sometimes you can't find them. However, bison, elk (in the northern part of the park) are quite plentiful so are marmots and other smaller mammals. Bears and wolves are much more sketchy to capture. Sometimes you see them some trips you don't.
4) Plenty of wildlife, landscape and other nature photography opportunities exist.
5) Like most National Parks, if you get 3/4 mile up a trail the crowds thin out substantially. Go 2 miles up a trail and you will feel like Jim Bridger exploring the mountains for the first time. 3 miles up a trail and you'll likely feel you are alone on the Earth. (what I'm getting at, is most people don't get too far out of sight from their cars).
As with any other location, I would advise doing research on what you want to photograph and what times of year are best for that. Example, you're not going to be photographing mama and baby deer in October nor would you be shooting fall colors in April. Those are extreme but figure out when your chances are best for what you're interested in and try to plan your trip accordingly. Conversely, if you are limited and can only go at a certain time of year then research that's happening around that time of year and plan accordingly.
So, is Yellowstone worth it? If you are prepared and have reasonable expectations, then yes, it is.