Beautiful, touristy and, to be honest, a bit expensive. 😀 The Casco Viejo is the centre of tourism in Havana. Here you will find most of the beautiful and chic buildings (e.g. Capitolio and Correos), as well as the most impressive and beautiful squares, famous hotels, bars and cafés, and most of the sights.
I’m not usually a big fan of places where there are lots of tourists or I find them overrated. Casco Viejo however is really beautiful. Of course you notice a difference to the rest of Havana when you leave Casco Viejo, but even so, Casco Viejo still has the Cuban vibe of Havana – even though it’s the tourist zone. The differences here are more that Casco Viejo is much better maintained and, especially close to the sights, really polished to almost shiny. Accordingly, it is also more expensive. Therefore, Casco Viejo is not overrated, but simply less the ‘real’ Havana with the authentic Cuban life that you see when for example walking through Havana Centro.

Go or not? Definitely go. Casco Viejo is really beautiful and has an incredible number of cool things to discover. From viewpoints to the hotel where Ernest Hemingway always stayed, the super famous bar ‘La Floridita’ and so much more. Don’t miss any of it. I would still recommend also exploring outside of Casco Viejo, because all of Havana has beautiful and interesting corners. Not to forget the authentic Cuban life happening on the streets. Also you can sleep and eat there way cheaper than in Casco Viejo. You’ll save a lot of money trust me 😀