I stayed in Imatran Kylpyla only 1 weekend, but could relax there as if I had 1-week vacation. Nice spacious room, partly designed as cabin, visit of pools and saunas included in accommodation, splendid surroundings with forest and lake. I would recommend to take a bike and ride around, even to the center of Imatra along picturesque banks of Vuoksa river. Though bicycles hotel has for rent are far from ideal.
In June restaurant was under renovation, everything looked a bit tangled and not so well organized, but still it was working and the breakfast itself was rich and with lots of Finnish dairy products.