The first Black Archive reviews are in and pretty damn fine they are too. Sci-fi Bulletin has reviewed each of the first four titles:
The Ambassadors of Death
Dark Water/ Death In Heaven
And gentleman and scholar Nick Campbell has a further look at The Ambassadors of Death here.
Obviously, after reviews like that you'll be wanting to pick up a full set so here's the handy dandy link to snaffle all four of the launch titles.