I stayed at the Lindner Hotel in Cologne during my trip to the Summerjam Festival which was located in the central and it was a really lovely hotel! It was very very clean and I liked the modern decor.
The bathroom was also pretty much spotless with all the things you need. I also liked the collaboration with Nivea (my favourite skincare brand), but the odd thing was that the product they had available was only for men.
There were 3 of us in a room (sorry I forgot to take a photo before we settled in!) and I anticipated it to be a small room but it was huge! Again, super clean and the bed was very comfortable. One little thing that bugged me were the curtains which were quite ugly but everything else compensated for it!
The restaurant area was nice but the breakfast buffet, although delicious with a wide variety of food, was very pricey - I think it was $35! ...great for those who can eat a lot in one go and will be full for most of the day, but not for those who can't!
Overall, I would definitely stay at the Lindner Hotels again but will consider eating breakfast somewhere else - or have it as part of the room package which I'm sure would have been much cheaper!