We did both the old town and Jewish quarter tour and the Charles bridge and Prague castle. Karla our guide was really great. It is clear that she loves her city and country. She is very knowledgeable and did not mind answering questions. We learnt a great deal from her. The pace was easy to stay with and she makes a point of keeping the group together. She is very considerate and made sure we did not block the way for others. It is really free. You can make a donation which I gladly did because it was really worth it. You should book before the time even for the free tours at their website. Just google Prague extravaganza tours. It is really worth it.