Drwęca is an extremely interesting river: meandring, with quite lively flow, relatively picturesque. You need to carry kayaks in only sporadical places such as Sambrowo. Sometimes you can meet rapids at the river but don't expect crucial sections.
Despite of the fact that whole river is a part of nature reserve, this formerly one of the clearest rivers in Poland is nowadays strongly polluted. There is no problem in finding a place for a camp, nevetheless it is better not to wait with search till the last moment.
The second unquestionable advantage of this route is it's unusual historical values.