We usually always make reservations, but spontaneous visits are usually no problem, depending on the time of day and the time of year. It's also possible to order food for pickup via Wolt (I think).
Upon arrival, you'll be greeted very warmly in the entrance area on the canal side and then shown to your table, or to a free table without a reservation. Seating is available both inside and, in the summer, outside on the two-story terrace. If it's a bit cooler, you can ask for a blanket. Ashtrays are also available if needed.
As for drinks, soft drinks, homemade lemonades, standard beers, wine, and cocktails are available. No one will go thirsty here.
The burgers and side dishes are mid-range in price, but you also get a lot for your money. Both the portion size and the quality are second to none. The cheese, for example, comes from the Hafenkäserei in Münster, and the other ingredients are also mostly sourced locally. As for the food on offer: there are all sorts of burgers (gluten-free, vegetarian, and vegan if needed), potato fries, sweet potato fries, nuggets, and much more. It's definitely worth taking a look at the menu (it's available online in German and English).
The ambiance is great, and especially in the summer, sitting on the terrace in the evening after a really good meal is incredibly pleasant. When it's busy, the noise level is naturally a bit louder, but still far from that of a construction site or a nightclub. Otherwise, the restaurant is tidy and clean.
The staff are very friendly, seem extremely satisfied with their work, and will go the extra mile. This is reflected in the quality of the food and service.
We've eaten at Hochstapler several times and would definitely come back.