When it comes to full-length modern Grant bios, there are quite a few to choose from (ex. Perret, Brands, Smith, Simpson, and McFeely) along with a host of shorter treatments and comparative works.
Ronald White, who announced his own effort back in 2010, will soon put his hat in the ring with American Ulysses: A Life of Ulysses S. Grant (Random House, Fall '16). It's too early for details but the first link offers some hints about the author's views.
Biographer extraordinaire Ron Chernow is also working on one and it will be interesting to see in what ways these two well regarded historians set themselves apart from their predecessors.