To start with: level-set your expectations. I have been on multiple five-star Nile River cruises and none of them are the same five star that you can expect on-land. I like to think of it as over-glorified camping. Once you accept that, and prepare yourself accordingly, this is a once-in-a-lifetime experience to see some of the richest historical sites in the world.
Remember, this a smaller river cruise ship...not a giant ocean liner. The cruise line will be adequate. It will be clean, have a sun deck and a working small bathroom. The staff will generally be friendly and attentive. Don't expect too much more. It's a clean place to sleep. At the end of the day, you will be so busy with activities and seeing the sites, that you won't really be spending all that much time on the boat, but for maybe an afternoon while in transit/sailing.
The food will leave something to be desired. It's not inedible or unclean, but it's certainly not gourmet. It's a buffet.
For us, the biggest negative was the other passengers during mealtime. They were pushing, shoving, and generally rude as soon as the meal time hit. This creates an arms race of people grabbing heaps of the good food because they didn't want to have to brave the buffet line twice. Honestly, my spouse and I felt like we were farm animals feeding from a trough because of this. We tried showing up later in the meal time, and got attitude from the staff (unacceptable). The meal services staff arbitrarily decides where you sit, which is common on any cruise as they want to keep people who booked with certain companies and speak certain languages together. Our issue was that they kept changing where they wanted us to sit...they even asked us to move arbitrarily after we sat down with our food from the same table we had sat at before to another table when we were there at the end of the meal time and nearly all the tables were empty. We didn't want to be 'those guys', but we picked up McDonald's and ate it in our cabin in peace for one meal because we simply didn't want to deal with the buffet onboard.
At the end of the cruise, the meal services director asked us to fill out a survey (which was only available in French). We filled it out and did not put our names, wanting to remain anonymous in the spirit of an accurate survey. The meal service director gave us attitude AGAIN for that.
You will have an exhausting experience. Your wake-ups will be 0430 or earlier and the days will be long...there is TONS to see and do. But, it is an amazingly rewarding and enriching experience to see the sites. Trust me on this, you do not want to opt out of anything during this cruise and it is absolutely worth the lack of sleep for a few days.
The absolute highlight of our experience was our guide, Amr. His passion for Ancient Egypt is contagious. To be honest, by the end of this kind of cruise, all of the temples and tombs tend to start blending together a bit...kind of variations on a theme. That and the lack of sleep can make it difficult to get excited about the sites sometimes. Amr kept us excited and attentive throughout...he was excited, piqued our curiosity, and answered our questions throughout. His love of Ancient Egypt and his ability to 'nerd out' (in the best way possible) and go off on tangents about all things Ancient Egypt absolutely made the trip for us. Remember, this is an educational experience...expect this to be like an interactive history lesson in the actual historical sites. If you are not expecting this, this kind of a cruise may not be for you.
Your tour guide will ultimately be the biggest variable in your experience. Your group's relationship with your guide should be a two-way street. Given that, Amr adapted and changed the itinerary for us based on our interests and desires. Amr was super kind to us, really showing us the famous Egyptian Hospitality at its finest...he even went the extra mile to come with us to the airport at the end when we were running late to make sure we didn't miss our flight. If you are lucky enough to get Amr as your guide, I promise you that you will have an amazing cruise...he made the grin-and-bear-it elements mentioned above more than worth it.
In summation, go into this cruise prepared both mentally and physically. Your guide and your own mindset will determine your level of enjoyment. And ask for Amr as your guide!