If i could rate Tripadvisor/Viator experience and Tour experience desperately, I would rate Viator with a 2 star and Tour with 5 star.
Due to some issue with Tripadvisor software, our booking was not send to the Tour Company booked the day prior. So there was no one at the meeting point City Hall for our 11 AM tour. But Mike, our Tour Guide, showed up as soon as possible 40-45 min later after we called him. The next 2 hours we blame Tripadvisor/Viator was a excellent tour. Thanks to Mike, our Tour Guide.
It turned out to be a private tour as we - a group of 6 people - were only booked the 11 AM tour. Mike took us around Milwaukee - from Miller park to Purple door to Beach drive to light house - while explaining each and every details. The weather was excellent, we could witness the color gradient in the Lake, Miller Park was free - we were in Friday box, Black Cat Alley was left to us only, Purple Door was not that packed. At the end, we were happy to have chosen the ride.
Please make sure that you call ahead so that you wont face the situation that we had. Tripadvisor seems to have this issue. We lost about an hour due to this error. We ended up skipping the Brewery tour and food tasting and chose to go with Purple door, Thanks Mike.