We paid for a first class ride (but through a discount website, for like $10 difference? I still don't understand the pricing) that had us on a regional train then a local train in Germany. It was a new experience for us and came after about 20 hours of flights and layovers so we didn't want to have a challenge to arrive.

On the local train we were unable to take luggage into first class (a small number of seats blocked off by a plexiglass entrance), but folks were very accommodating of some clueless Americans just trying to go a few stops down the track.

The regional train was nice, but second class on the way back from our destination was just as comfortable.

Long story short, the claims of comfort and cleanliness between the classes didn't really seem apparent.