We booked this cruise because we wanted to experience the Rhine and nearby sites without hassling with trains, nightly re-packing, trying to decide where/what to eat, how to navigate local connections/transportation, etc. -- that has often consumed our other European trips. We wanted a splurge trip that was relaxing and stress-free, yet offered chances to see towns and culture along the way.
Short version: AmaWaterways fit the bill perfectly! We were further delighted by the high level of friendly service. Our needs and questions were addressed promptly and well. The food (good variety) was on par with any other cruise we've taken (Alaska, Mexico (x3), China); and the beer/wine/champagne was inclusive. The cruise offered a selection of two excursions per port, plus usually an "active" bicycle tour (we didn't take those). The excursions were inclusive, also. We didn't feel nickled and dimed; and the gratuities are at your discretion (not "automatically charged"). We didn't take the optional trip extension, as we wanted to do our own self-guided addition (but that's available on some cruises, apparently). On a couple of excursions, the guide gave a little too much history to digest, but we've encountered that on different trips where we've paid on the spot. Still, the local connections were usually flawless. The Internet worked most of the time, but was sometimes down due to a specific location.
ANOTHER IMPORTANT SUMMER CONSIDERATION: Unlike many hotels and restaurants in parts of Europe, your cabin, dining room and public areas are air conditioned. Even if it's hot while touring on excursions, you can at least retreat to the ship, shower and recover. If you don't take heat and humidity well (like my wife and I), consider the value of this advantage.
This Rhine cruise was our second river experience, inspired by a Yangtze cruise in 2007. Taking that, we realized something -- we were not stressed out by traveling as a couple, and could actually enjoy the sights. Let's be honest: you can get a "cheaper" trip; but you'll pay for it with your stress, arguments and uncertainty. If you want cheap, don't take a cruise.