There are pro's and con's but the more we understand their habits, and the more research that comes out, the pro's unequivocally outweigh the con's, particularly when you look at the big picture.
The description of beavers as 'ecosystem engineers' and a 'keystone species' is no overstatement. Their dams create pools and riffles and important variations in flow, as well as increasing important deadwood for invertebrates. Their coppicing can increase light levels improve the biodiversity of the riparian zone - lots of knock on benefits for birds and butterflies.
We need to better understand how to manage potential conflicts between beavers and localised land use, and beavers aren't the panacea to all the issue facing our rivers, but they do offer enormous benefits. The work that comes out on the benefits they offer, the more utterly foolish the Angling Trust look for their anti-beaver stance back in 2014.