I am a Norwegian and have been there 2 times before. I have ordered another 9 day stay at the end of September 2014.
Pod Tezniami is a very good hotel with lots of possiblities for treatment. Highly skilled medical staff, sets up a program for you on the first day. There are three swimmingpools. Massasje, gym, hairdresser, pedicur, manicure, dentist. The rooms are nice with TV (1 or 2 english channels), bath and a fridge. Internet is of decent quality.
The restaurant is superb, with high quality buffet three times a day. In the evening there is a popular bar with live music. The polish people is known for dancing, so there will be full dancefloor every night. The bar close at 22, and the SPA/Sanatorium get quiet.
There is a small shoppingstreet, several restaurants and bars nearby. The city is crowded in the summer, so a good time to relax and get treatment is maybe outside the high season.
The doctors speak English, some of the staff don't. If your polish is not good, use Google Translater.
The Sanatorium offer pick up transport from the airports. A bit high if you travel single, 500PLN. It is a 2 hour drive, but you can get there a lot cheaper by train and local taxi..