The new series is up to #6 now, and although each issue is in itself a stand alone adventure there is an overarching storyline to it all.
The regular series, written by Chris Roberson and illustrated by Bilquis Evely, is quite good. Each issue progresses the timeline by approximately a decade (starting in the 30s with #1) and tells what Doc has been up to in the interim while setting the stage for the current action.
The annual issue, written by Shannon Eric Denton and drawn by Roberto Castro, does not measure up to the regular series in quality of story or illustrations (imho). The enthusiasm was there, but was missing the mark.