we took this tour as there was a groupon deal. I read the reviews and took a chance. I have to say i dont repent my decision. First of all the Guide (Yohanes) was really helpful as we have two other family members who were running late, he waited for 10 minutes for them and finally we all made it to the tour. Generally the tour buses/companies don't wait for more then 1-2 minutes. The van is pretty good and seat ~8-10 people comfortably. One thing i have to mention is that he is very knowledgeable and takes keen interest in telling you the details/history of DC just not dropping you off the shuttle bus. If you forgot to bring you own water, he will have some reserve so that you dont end up thirsty. Couple of places where you wont see the hop on / off buses wouldn't go you will be able to see if in this tour like the historic Georgetown. These are the places where we stepped down and got the oppurtunity of photos:

1)U.S. Capitol = NO (from van)
2) White House = Barely 5 min, (due to rush hour traffic)
3)Lincoln Memorial = ~15 min,
4) Vietnam Memorial, Korean War Memorial = No (from van)
5) FDR Memorial = Yes (~10 min)
6) Iwo Jima Memorial = Yes (~10 min)
7) Airforce Memorial = Yes (~15min)
8)Martin Luther King Jr. Memorial = Yes (~10min)
9)National Cathedral = 5 min for photos from outside

It would have been good if we could have got more time near the white house but due to the rush hour we hardly got any time to take the photo graph, same happened with the Korean War memorial.

This is what i recommend , if you are ok skipping some of the photo stops and interested in learning the history you wont get disappointed by this tour. Guided tour is really good.

If you want to spend more time on every place with photos etc, i will recommend hop on/off bus, just make sure that you start your tour in the morning but you wont get the luxury of detailed history of the DC monuments :)
Enjoy.

We enjoyed this tour very much! Our guide, Yohannes, was knowledgeable, interesting, and thoughtful. It was the perfect balance of sitting, and getting out of the van and walking around the different places. The four hours flew by! Besides the great tour, we appreciated Yohannes giving us useful tips for our time in DC, dropping us off at our next destination, and offering to help us in any way during our stay. We would definitely recommend this tour!