We took a similar tour in Seattle, and this one was even better!
Our guide, Bryce, was extremely knowledgeable and lots of fun. He is young and looked like a bit of a partier so I was initially concerned that there wouldn't be a lot of beer education, but those fears were immediately put to rest. Bryce knows a lot about beer and the chemistry of beer making and was able to explain difficult concepts in a fun and engaging way. It really was a mini science lesson. Bryce is an excellent teacher. He managed the group well, put us at ease and by stop #2 everyone was joking and chatting together. Bryce isn't afraid to poke some fun at you but never were we made to feel silly.
The value was also good: the samples were generous and if you finished quickly and liked a particular beer, there was often a second sample available.
A couple of notes on the logistics of the tour: we started at Rockbottom Brewery and it was a long walk to the second stop. Wear sneakers! At the end of the tour, you then have quite a long walk on your own back to 16th street - bring a map or ask for directions before you leave the last stop. I think our tour was meant to end at 5 but when I looked at my watch at the last stop, it was after 6! I don't know if that is a usual thing or if we were all having too much fun to notice time flying. Also, with your ticket, you get a coupon for a free beer at any of the four stops - but there's no time to have an extra beer at any of the stops other than the last one. I don't know if you can go back to other ones after the tour or not.
This is a great activity to do in Denver, especially if you are on your own and/or want to learn more about beer brewing. Definitely recommend.