Everything that I can say have already been written in the earlier reviews, but once again - this really is an awesome tour, one of the best free walking tours I have ever attended (and I attended many). I feel like this city walk has been a solid foundation to exploring Buenos Aires further. No matter if your stay here is going to be short or long - take the tour and you either get nice idea where you wanna have a closer look next days, or, if you are leaving soon, you get a nice overview of the most important landmarks.
Jonathan is a great guide, you will get tons of information about Buenos Aires and Argentina, their history, culture, politics, ... and also great practical hints! It's like a mine of information - seems that you can ask any questions and get the answer :)
Thanks to Jonathan for a very nice afternoon in the city - sure I will recommend this tour to anyone who is visiting BsAs!