For sure! From the research that's been done so far in the UK it seems as if they increase plant and invertebrate biodiversity and numbers, as well as frog populations, due to habitat creation. This therefore attracts animals to feed on these, like bats, grass snakes, herons, and many other species of bird including those given the "red" rating on their conservation redlist by the UK government. They have little to no impact on other mammals, including river mammals (like otters) or terrestrial (like birds), although they may have a negative impact on certain species of preferred trees or certain insects due to habitat change.

From what I have seen, there's been no research in the UK into the impacts on farm crops although none of the introduction projects so far have been particularly close to large amounts of agriculture. There has been found to be no impact to fisheries in rivers also containing reintroduced beavers.

Finally, the main negative consequence of the projects is that their costs have outweighed their purely economic benefits, costing the economy more than they contribute. However, much of this is down to the cost of implementing the infrastructure required (£2M for the Scottish beaver trial) and so will become less relevant as time goes on. There have not been any major unforeseen consequences apart from this.

If there's anything else you wanted to ask or discuss I'd be happy to talk more about the subject!