We stayed for three nights in December 2005. Our double room was perfectly clean, and the room was up to 4-star standard. The hotel is located 1 minute from the Barrio area, so you're in a perfect location for late night fun.
Our only grumble was the noise from the traffic. This isn't something unique to the Plaza, but generally in Spain traffic noise has a habit of getting past no matter what type of double glazing is installed. Since we were often out dancing until 4 or 5 am, the possibility to have a siesta was important... and it wasn't easy!
The hotel staff were polite, friendly and it was no problem for them to prepare the sauna should you ask. We found that by booking through a Spanish-language website we got one night free and in the end paid about EUR160 less than what we had originally paid through an English-speaking website.
The view from the roof-top gym is perhaps the best in town... overlooking the town hall square and upwards towards the citadel.