First I have stayed at far worse places in Italy for over 100 euro per night. You should see what 100 Euro gets you in the center of Venice.
But I think this is a matter of the website you are dealing with and possibly a bit of misrepresentation by the hotel.
You said you had a good experience with Priceline. What does that have to do with lastminute? LastMinute.com is a UK company using European standards for the their hotel. Priceline on the other hand is using U.S. quality based standards when ranking hotels and when they misrate a new hotel they go out of their way to make it right.
LastMinute took over U.S. operations of the formerly great website Site59 but their new system leaves a lot to be desired.
Now here is what the hotel
says their rooms look like.
That is very different from your pictures.