Actually, I have been visiting Merkur since 1997. However, this place is NOT a hotel! It is a kind of medical facility aimed at keeping patients in a more comfortable rooms than in a real hospital.
As a medical resort it is great! Doctors and nurses will really try to help you and they also succeed in helping by applying different therapies and approaches, and they are really kind.
However, the rooms are old and/or very badly and poorly renovated! Many things make no sense and the people being responsible for the rooms simply do not care! This place is mostly fitted fro those being sent for rehabilitation with all costs covered by social insurance . The swimming pool is filled with mineral water, which turns green within hours and looks terrible, and nobody will explain you why it looks like that. The sauna is being used by kids! and by people who have no idea how to use it, and even worse: the personnel has no idea! The gym is small and some of the equipment is dangerous to be used!
One of the good things (maybe only good thing) is the food. It is not served in fancy dishes but it tastes great and it helps you loosing some weight!
In summer, the music is extreme loud from surrounding bars and nobody can sleep.
Therefore, do not expect to find anything like on pictures.It is a terrible place in any aesthetic term but if you need medical help for heartburn or diabetes this is the right place to be. You just need to close the eyes and simply go through it and ignore all the terrible things once cannot explain but only through one's hands in the air.

As much as we hoped that this place is like in pictures the biggest impression is that hotel is deeply stuck in 80`.
Its big, with comunist architecture, partly renovated, and resembling of old days. Since this place is good for diabetics, guest are mostly older and its not realy for younger families. There are plenty of different foods but still a lack of a bit modern aproach of cooking and presenting everything.
Pool was not in a good shape, it was still not cleand for season, and there was lots of rust around it so you have to be very careful when walking bearfoot. My husband was very pleased with sauna but general impression about wellnes was a bit on a down size.
We had an apartment with living room toilet and bathroom and huge terrace. Bed was uncomfortable it was craking on the single move we made, interior was ok, sofa in the living room was comfortable and terase was nice for relaxing. Water in the bathrom was not the hotest one so if you have a child wait till it gets warm enough. Cleaning ladies were very polite and gave us clean towels every day, reception staf was also helpful.
There is hotel parking but they are charging you 100din about les the 1eur per day. Wi-fi was free and conection was good. Hotel is in the center of Banja in nice park so you can have a nice walk.
All in all Hotel Merkur could and should be on much higher level just by investing in important things and folowing trends in runing a big Hotel like this in very competitiv hospitality environment.

Location of the hotel is excellent, in the hart of Vrnjacka Banja,
service is ok. rooms are very comfortable. Food is also very god.
Aqua floor is ok. sauna, swimming pool with mineral water and volcano place.