36 hours in Prague is not much time, especially if it's your first time, you don't speak Czech, and you don't want to spend your day hoping your guidebook is good enough. You'll probably have fun, sure, but will it be worth the trip?
This was the case for me, as Prague was a brief excursion on a multi-city trip thru western Europe. And having spent more time in other cities on the trip, I can honestly say that I saw much more of Prague, than I did in other cities, even having spent 2-3x as long in those places.
Marketa is the person behind Caput Regni Private Tours, and I don't see a single positive comment that I'd disagree with; she's incredibly responsive, helpful, and simply runs an excellent business. Likewise, the guides who work with her, seem to deserve their positive reviews. My tour (a 6hr day) was with Lea, and clearly enjoyed being there to provide a tour, and amongst our informal discussion, was very complimentary of Marketa.
Is it worth it? Well, it's not cheap, but it depends what you want to get out of Prague. For me, yes, it was. It would've been a rather boring detour with cheap beer; instead, I listed my goals, we did a fairly expansive tour, and enjoyed the conversation in between. Had a good time all around, and would do it again.
Bottom line, if you think a local guide - and not just a "hop on / hop off bus" - will be a benefit, then I have no hesitation in saying, talk to Marketa, and know that you'll have a much better time in Prague.
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