This was our second cruise with MSC and our third overall (Disney Dream was our first). I had originally booked a Bella Balcony cabin but was upgraded somehow to YC1. We ended up in cabin 16033. The Yacht Club experience was more than we had ever hoped for. It was so good, in fact, that we will probably try to go YC again if we can even remotely afford it.
If I were to try and find some negatives about the experience on the Splendida and the YC it would have to be the food in l'Olivio. It was OK but aside from some interesting choices it was lacking in overall choice. The service there was excellent, however. Another negative was some timing discrepancies in when food was available in the lounge buffet or the pool deck buffet as well as some report times for various activities. Thats it. The rest of the experience on the ship was top notch.
Excusrions were hit or miss. Most of these are of personal taste. Do your research before you commit. Note that the more cruise ships in port the less appealing the excursion experience will be.
We had the basic Allegrisimo drink package and used it well outside of the YC area. In our case it was worth the cost. This time it included gellato as (IIRC) last time we cruised on the MSC Fanstasia it was not included.
Other advantages to the YC is having the express elevator at the bow of the ship and the ability to cut to the front of the line when embarking.
We will sail with MSC again and will book the Yacht Club again, as well, if financially possible.
The YC cabins are great. Get one on the side because (I believe) the ones up front have plexiglass wind deflectors. Maybe someone can correct me if this is not accurate.