There are two separate wings here: the Sava, with 'superior' rooms, and the older rooms of the Zagreb. The Sava's rooms are some of the nicest and most comfortable in town, all peachy-beige tones and leafy views from the balcony. Don't bother with the Zagreb wing; rooms could do with a refurbishment.
Guests get free entry to the hotel's Lotus thermal baths. Despite the high rack rate the hotel often advertises cheaper packages and discounted room rates online.