The problem here is that by its nature, moving 4,000+ people of different nationalities, ages, languages and classes around the med is a logistical nightmare and for MSC to get it even 80% right would be a miracle.
So starting with the Booking, it was easy to do and the booking staff were patient. However, the website is very poor being just a poor translation of the Italian one and customer feedback on the booking process is seriously lacking. Expect problems such as non-receipt of the confirmation email, misspellings of names and addresses and no tickets until after you complete the booking confirmation email questions.
You cant select your cabin or flight in the same way as you might select a concert booking. Packages and excursions are heavily marketed but there are very few hard facts about them. e.g. What time do they start, what sort of lunch might you get etc.