Pros

Perhaps most importantly, it allows you to see things at your own pace.

Since you choose your own tour stops, spontaneous sightseeing is possible.

Based on preference and physical capability, you can choose the amount of walking and climbing you do.

You determine when and where you eat.

It need not be obvious that you are a tourist.

Your choice of companions can be yours alone.

Paying a guide won’t be necessary.

Cons

When visiting somewhere you have been to countless times before, you may not have enough local knowledge to find something new to see.

If your destination has a reputation for dangerous or unpredictable street life you may find yourself in jeopardy.

There may be a language barrier you are not able to cross.

Suggestions

Many cities around the world offer “Hop-on Hop-off” tours that continually drive around defined routes. Visitors can use their ticket to jump on at any stop and can get off at whichever stop they choose. This gives you the freedom to create your perfect itinerary using a private door-to-door coach network. Pre-plan your trip or wing it as you go. Change your plan as often as you like, free of charge. While on the bus the passing and upcoming landscape is described by tour guides who are entertaining and informative… if they are there in person and speaking a language you understand. If the information is being provided on recordings in your language that you can listen to with earphones, the experience is far less enjoyable. Nonetheless, Hop-on Hop-off buses are a great way to get around to see a city’s top attractions.

A self-guided tour is a good choice when there’s a popular established way of traveling through a specific region, like the Camino de Santiago in Spain. If you can follow a clear trail and there are other people doing the same thing, self-guiding is perfectly reasonable.