I have stayed at this hotel several times last year on business trips. The overall impression is very good, although were I to pay the price myself, I would probably expect more from a 5 star hotel.
On my very first visit the hotel might have been rather empty as I got an upgrade. That room was really spacious, almost a bit too big for one person - separate toilet, a shower, a jacuzzi bathtub (which was, however, not entirely clean, so I ended up not using it...), tv in the bathroom. The decor is not to my taste as it is rather old-fashioned and has too many golden elements in it.
On the other occasions I got rooms on the second floor, with windows onto the street. The heating/air-conditioning did not seem to work very efficiently as it was very hot in the room and at the same time quite windy; even if I turned off the air conditioning with the panel I had in the room. I needed to open the window which meant noise from the street but if you close the blinds, it is bearable.

On two occasions I also had to spend weekends there so I would have welcomed the same 200-something tv channels to choose from which is available at all other, much lower rated and priced hotels in Lausanne I have been to. But instead here you only get a crappy hotel tv system with tens of arabic and russian-speaking channels (so you can have an idea of the preferred clientele here) and not a lot of quality tv channels in other languages, which is quite disappointing. Also, the remote ceases to work properly after having changed channels about 5 times, so a reboot is necessary..

I only tried the breakfast once because the price is just too high. And honestly, for that price I would expect much more than I got in the end. I had much better breakfasts for a more reasonable price at other hotels.

The gym and spa area is very clean, modern and not too crowded. As a hotel guest, access to these facilities is free of charge but as mentioned by others, you need to change in your own room because lockers are not provided for hotel guests. But this is not so bad. As I am a passionate swimmer, I really like the 12m pool which is almost always empty in the mornings. Sauna, steam bath and jacuzzi is available separately for men and women and is also nice and clean.

I tried 2 restaurants of this hotel, the brasserie and the cote jardin, both served delicious food (I am not complaining about the price which was high enough but it is Switzerland).

The hotel staff generally is very friendly and they were very helpful in organising a visit from a doctor for me when I needed one.
You should check the hotel bill carefully because once they wanted to charge me for a room service bill that was not mine (the bill was not even signed by anyone) and my colleague had the same experience once or twice. But they do the correction if you spot the error, so in the end it was ok.