Starting at 10 am and costing 850CZK, this lasted 6 hours and involved maybe 3 hours of walking, lunch (plus a drink), a small boat cruise, a tram ride up to the Castle and a CD with photos of prague, included in the price.
I can't compare it with any other companies, but I was quite satisfied. The walking covered the Old Town, Jewish Quarter including 5 synagogues and the cemetery, then after lunch and the boat cruise we crossed the river and went up the hill to the Castle.
There are lots of other walks available too. If you want to contact the company, they are:
Entertaining Walks of Prague
Dobraticka 523
19900 Praha 18 - Letnany
Tel +420 737 884 745
email: walksofprague@email.cz
Alternatively there are lots of leaflets available, and I'm sure you'll find something worth testing out!

