Sushiou has been one of my favourite eating planes in the last few months. It's a sushi bar with one of those conveyor belts that goes round and round (回転寿司 kaiten-sushi).
The fish is fresh and tasty and the sushi is prepared out in front of the customers. If what you fancy is not on the belt, you just need ask for it. The range available is excellent, in my opinion. There's also some sashimi options and a handful of non-sushi items such as miso soup (of course), seaweed salad, fried chicken and fruit salad.
The nigiris are made with quite a small rice ball compared to some places, which, as far as I am concerned, just means you can eat more! I confess I like nigiri and don't eat many maki, so I can't say much about those, except for the Ebi Tempura maki which is consistently delicious and one of my favourites. Others at the top of my list are the Saba, Hamachi, Maguro, Toro and Unagi nigiris.
The owner and staff are not Japanese and the sushi is occassionally a bit experimental and not 100% traditional, but that isn't a bad thing. The current "special" is seared salmon with a sliver of avocado and a creamy, spicy sauce. Not for the purists I guess but very tasty!
Best of all they have an "all you can eat" option for about €25. 12 plates is about my limit, but since I generally go for the more expensive ones, I feel that I get very good value for money. Someone with a bigger appetite could really go to town.
If you are in Cologne, check it out. It is definitely worth it.