Don't dismiss this, necessarily, because it has only 126 pages and such a presumptuous title and subtitle ("And What Jesus Really Said and Did"); we have to be fair because we are promised that it is a prequel to a larger volume upcoming.
Not that this early entry bodes well for what is to come. Gerd Ludemann has compiled a collection of sayings of Jesus which he analyzes and supposes to prove which of them were or were not said by Jesus. By percentage, the Jesus Seminar probably gives more to Jesus than Ludemann does, but his reasons for "unassigning" words from Jesus are no less compelling.
The two most basic "disassignment" criteria are no more than begged questions: 1) anything miraculous is not worthy of belief; 2) what Jesus says here sounds like it would serve this writer's "community" -- i.e., it would serve what Ludemann has decided this community, for which there is not a shred of literary, archaeological, or social evidence otherwise, needed to justify its stance, so it was obviously invented.
Works by authors we have recommended on this page (Witherington, Bauckham, Wright, Blomberg, etc.) provide all the antidote that is needed to refute this effort by Ludemann -- and I don't have to tell you that he hasn't interacted with the "other side" of the arguments at all.
-JPH