We did the reverse Heart of Europe cruise, from Budapest to Cologne. This seems to be the preferred direction, giving longer in the ports enroute.
We saw lots of other ships on our cruise, and, frankly, didn't see anything to compare with the Thomas Hardy (incidentally, we were also moored alongside the William Shakespeare one day and it is looking very old fashioned and outdated, despite only being 3 or 4 years old. The Thomas Hardy is in a different class). The ship is excellent, and the cabins ("suites"), whilst small, are brilliantly designed. The French balcony design works particularly well, transforming your cabin into a large balcony when the triple sliding doors are fully slid back. The room aircon is excellent. Only gripes, the TV is rubbish - a few news channels, a couple of local stations and bizarrely, 2 "God" channels, and the wifi is pretty poor; patchy and barely usable when we did have internet connection. The cabin was kept spotlessly clean by the staff, who did a great job.
The sun deck is really nice when it is open, which unfortunately, due to low bridges, is for a very short part of the cruise, the first 3 days or so and the last 1 or 2. However, the forward deck is kept open throughout, which is a decent sitting area at least.