Is it worth it take it or its much better if you do it on your own exploring the city? Because I just notice a lot of hostels in the southern part of Europe is offering walking tours everyday in the hostel.
I haven't taken walking tours organized by hostels, but I've taken quite a few organized by local tourist offices. I've enjoyed all of them. Great information, great exercise, and a great way to make contact with other travelers--though if you are staying at hostels in dormitory beds, you may already have the contact-with-others covered. Such tours are also an opportunity to ask questions of the guide, things like "What's the best area of town for inexpensive restaurants?"