Just stayed here on points and cash. Recognized as Diamond, got free drink voucher plus a further voucher for some Gluehwein with bread, as they have some special Christmas stall in the lobby.

I stayed in some main Hiltons in other big German cities as part of the same trip and my wife felt that the HGI room was the best!

This was my first stay at an HGI and beforehand I didn't realize that the stated benefits are free breakfast OR 750 extra points. I asked the front desk and they seemed to imply that breakfast was free for everyone, but didn't really answer the question about whether I would get the 750 points as well. However, my HHonors balance also increased by 1000 points more than expected for some reason.

Rather than going to Bad Canstatt and searching for a bus stop, you can take the S1 one stop further to Neckarpark and walk 15 minutes. The hotel is very easy to find if you know where you are going and you aren't in a moving vehicle with limited visibility.