A cautious verdict on The Lost Fleet

What is the verdict on Jack Campbell's Lost Fleet books?

Only the first book had been read, and the lack of further reading is offered as a cautious sign that it did not engage strongly enough.

Jack Campbell's Lost Fleet is assumed to be the series meant by the question. Only its first volume had been read. The decision to stop there is offered as a cautious indication that the book did not leave a strong enough impression to continue. The later volumes therefore fall outside this personal verdict.