Much like the first IDW story, this is very long, but they do a much better job of marrying up the episodic stories with the overall arc. It is constantly going “remember this?” so probably wouldn’t be a good read unless you have a PhD in Doctor Who. The extended universe has many, many examples of multi-Doctor celebrations that do a lot of looking back, as far as they go this one is good and gives each Doctor a moment to shine. The iterative nature of the story though means that there isn’t a compelling plot to follow or anything like that.