We stayed at the Nacional from Feb 5-12 after a fascinating week-long tour of Central Cuba. Our travel agent booked the whole package with Signature Travel. It was our third trip to Cuba and our second to Havana (previously we'd stayed at the Sevilla on the edge of Havana Vieja).
It's true that this landmark hotel is full of history, the public areas are beautiful and the views from the room impressive. However, the room we stayed in (518, I think) was in dire need of refurbishment - the carpet and drapes were stained and there was a mildewy smell that could only be temporarily removed by leaving the window open to air the room. If we had been staying more than 7 nights, and if the hotel had been less busy, I may have requested a room change, but judging by the hallways and quick peeks into a couple of other rooms, ours wasn't the only one in need of an update.
We found the service in the lobby (concierge and reception) to be not very helpful or friendly, for the most part - although a kind woman at the management desk did help us to locate our missing Signature rep (she didn't show up when she said she would, or perhaps it was just a misunderstanding). The food was, overall, very good for Cuba, I thought - since our breakfast buffet was included, I'm not sure of the price so can't comment on value for money. The cabaret show was good, but in my opinion certainly not anywhere near as exciting as the Tropicana (which we saw on a previous visit). At this show, we chose the expensive meal option, and for $35 pesos extra per person (yes, I know - outrageous) - we ate a great meal - half a lobster, Canadian filet mignon done very nicely, etc.
We were supposed to stay at the Parque Central, so were a bit disappointed when we had to change due to a scheduling problem. If and when we return to Havana (who am I kidding - WHEN we return to that wonderful city), we will probably try the Central (or maybe the Saratoga). Staying in Vedado rather than Havana Vieja was an interestesting change, because you could walk down La Rampa, etc (can cab it to the old city - or walk, like we often did) - where you see a different part of the city - a bit less touristy - very few hustlers - people just going about their everyday business). By the way, the Hotel Isabella looked very interesting - very close to the Nacional - seems to be a smaller boutique hotel - read some good reviews of it. In Vedado you're also closer to jazz clubs like La Zorra y el Cuervo.
So - I don't regret staying at the Nacional, but we'll try the Parque Central next time, if possible.