This review is pretty negative but I did actually have a good time staying at Abel's house when I was actually there. However, I would like to describe our experiences and warn people about Abel, because he was not honest with us. I have seen lots of reviews from travellers saying he is a great person and friend, but I don't know if going to Cuba thinking that the people running the casas are your friends is a good attitude, however kind and hospitable they are.
I stayed in Abel's casa with my family last month. We arrived late at night and were told one of the rooms was taken because another couple had decided at short notice to stay an extra night (reading other reviews, this is not the first time this has happened so they probably didn't 'decide' at the last minute but he had double booked the room to ensure business) so my sister and I were sent to a different house, which was clearly not a casa particular, or even a home at all. We are not fussy or demanding at all and have both stayed in some pretty rough hostels in our time, but this was not roughing it, this was slumming it. It was almost indescribably awful. Because of how bad it was, we thought we would be given a discount at the end but we were charged the full price (35 CUC, NOT cheap and NOT the 20 CUC stated on the website, which clearly reads, "The nightly rate is 20 pesos convertibles (CUC) per room per night all year round. Our price remains the same during high season. We remain firm on this policy". AN OUTRIGHT LIE).
After that, we went to Abel's home where we stayed for 2 or 3 nights, I don't remember exactly. He is funny, entertaining and interesting (if cynical - he will show you around the grotty areas of Havana to give you the impression that it's all doom and gloom) and you can enjoy some rum and a drunken chat with him (him being the drunk one - he got through about a bottle of rum one afternoon), sitting in rocking chairs in the beautiful, high-ceilinged sitting room at the front of the house. His wife, Aidee is lovely, sweet and always smiling and I enjoyed her cooking very much, and there is another lady, Greta I think, who is also very nice.
However much fun Abel is, though, he is also very shrewd. When we left for Vinales, he convinced us that we would have a very hard time getting tickets for the Viazul bus, telling us the bus station was on the other side of town and tickets usually sold out days in advance, and that the cost of a taxi for the four of us would be around 3 CUC per person more than the bus (60 in total, 48 for the bus). In the end we decided to take a taxi and he immediately rang a friend of his to arrange it. Our mistake was not to confirm the price with the taxi driver before leaving. We were in the taxi, about to leave, when the door opened and Abel's grandson, also named Abel, told us to move up so that he could get in. He came with us all the way to Vinales, making it a very uncomfortable journey because of the heat, lack of space, springs digging into our legs, and Abel Jr's high-pitched 3-hour monologue. He was extremely annoying. He told us he lived in Vinales and we realised that he was hitching a ride in the taxi we were paying for, and he obviously wasn't planning to pay anything. When we arrived, we were charged 100 CUC and the driver (who was very clearly NOT a taxi driver but just a guy with a car with a taxi sticker, which you can buy in souvenir shops) refused to negotiate on the price. When we said that it was way more than what we had agreed with Abel, Abel Jr said that the driver had come to the house to pick us up and so it was more expensive. The whole thing was clearly set up by Abel just to give his grandson a free ride to Vinales and make some extra cash at our expense, and it was pretty disappointing to realise this. We did laugh about it afterwards, but it made us realise that we had to be careful not to think that people were our friends just because we had had a few drinks and a chat together, and that it wasn't a good idea to ask people for help.
My advice is this: If you stay at Abel's house, you will have a good time, be close to the centre and very close to the Malecón, eat nice food and enjoy talking to the hosts, but DO NOT tell Abel where you are going afterwards or accept any "help" with anything that involves money. Do not ask him for help finding a casa in another town, or getting a taxi, or changing CUC to moneda nacional (as a tourist, you shouldn't even be trying to use MN anyway). If you really want to take a taxi, find it yourselves and agree the price beforehand. Lie and tell him you are going to stay with friends, or have already organised accommodation in your next town. Also, be prepared to spend the first night in an absolute dump that not even rats wanted to live in.