The Three Doctors is a delightful bit of Who history. It wears that on its face, so I don't really feel the need to repeat the big production milestones this story represents.

I will say I largely enjoyed the story, from the Brigadier going into the TARDIS, to the Time Lords and Omega, it all just works for the story. Very familiar to what would later be used in DC's Crisis of Infinite Earths, which is interesting.

The Second Doctor is so great here and a huge draw of this story is just watching him bounce off of all the other characters, especially Stewart, The Third Doctor, and Omega. The effects leave a lot to be desired, from Blob monsters and pretty silly camera tricks. That's not even to mention the way that the First Doctor has to be sadly sort of stapled on to the story due to Hartnell's health issues. That's not really anyone's fault, but just an inevitable shortcoming to a crossover here.

Still, this was a fun time overall, and probably to date one of the better Doctor crossovers thanks to its underdog nature and the fact it was first up. Definitely worth watching for anyone familiar with the first three Doctors.