We have no complaints about Scenic at all, it was one of the best tours Mum and I ever did

Which cruise are you doing, Jewels of Europe??
The cabins are fantastic, even better if you can get a balcony! I'm sure you've read some of the posts which complain about the cabins up the back near the engines. I'm not sure how you can avoid that issue, though. Hopefully you'll get lucky like us. Our cabin was right in the middle of the ship on the Danube Deck; very clean, enough room for two and nice big balcony. We had to change ships half-way through the two-week cruise but this was no problem at all (we went from the Sapphire to the Ruby). All we had to do was put our luggage out early in the morning, go off on our day-long sightseeing trip and return to a port further down the river in the evening to the new ship. The layout of the two ships was identical and we got the same room that we stayed in on the first ship.
Some things I do remember:-
The showers were fantastic - good powerful flow of water and very nice toiletries, too (I think they were L'Occitane brand). If you need good light to do your make-up, the mirror out in the cabin is better than the one in the bathroom, because it has extra lighting around it's border.
Internet doesn't always work but this can't be helped; it all depends on where the ship is at the time. We only had trouble a couple of times. You can pay a small fee to have internet access in your cabin which is what we did. Note: if you are sailing on the Sapphire you can hire laptops; if you're on the Ruby there is a keyboard supplied in your cabin which you plug into the flat-screen TV to access the 'net.
A good tip: if you have a certain table in mind for dinner, make sure you get to the dining room doors
at least five minutes before they open! I have never seen such a mad rush of passengers heading into that dining room, it was like a January sale at a department store! If you and your companion do manage to get the table you want, and your expecting others to join you, grab the serviettes in front of the other seats and throw them over the tops of each chair. That way, nobody else will sit there. Also, on our last night on the cruise I noticed one particular group of passengers had
reserved a table. Nowhere in any documentation on the ship does it mention the ability to reserve tables for dinner, so either those guys paid a huge tip or they just got lucky! So keep that in mind if you like.
The food was fair; you get four courses to choose from (a choice of three dishes with each course): a starter, then soup, the main meal and dessert. If you have a bit of a hearty appetite, I'd suggest ordering something else on top of the main and dessert, because the portions aren't exactly what you'd call...big.
Most of the time (except at night) passengers are allowed to visit the wheelhouse and watch the Captain at work whilst having a chat with him. We had fantastic Captains, very friendly and down-to-earth. If you get Hans, he's fantastic
Only one little negative for us: the staff, for the most part, are very friendly and helpful. However, in our experience, there seemed to be a lot more staff on the MS Sapphire than the Ruby. Not sure why, but the Ruby was severely understaffed (only one waitress servicing over a hundred passengers in the lounge, as opposed to the Sapphire where waiters were everywhere). As a result of being overworked (perhaps??) the Ruby wait staff weren't all that friendly. You might be lucky, though. Also re the tipping - even though that is included in the Scenic fares we noticed a lot of passengers tipped extra to their cabin stewardesses at the end of the cruise (as did we; our stewardess Erika, on the Sapphire, was brilliant).
There's no big dress code on the ship, except on the first and last nights a lot of passengers tended to dress formally. There is an on-board laundry service - they do a great job but it's
not cheap.
The air-conditioning in the cabins wasn't all that brilliant, and we had some fairly hot weather in Budapest and Vienna. Trouble is, at night when your sleeping you can't leave the balcony door open because the mosquitoes will eat you alive. For some odd reason, there's only a glass door but no fly screen door over it. Anyway, the Captain mentions this during his welcome speech in the lounge.
I can't think of anything else at the moment. Sorry for the ramble, just trying to give you anything that may be of use.....