I've re-read the first four issues and given this one two passes. So how does it stack up?

Very well, actually.

Barry's solved his cold case. Zoom's not only ruthless, but petty and vindictive as well. The changes to the other characters work, including Wally's new costume (scans and commentary at that link).

The main thing I didn't like about this book is that it really feels like the story itself is less important than shifting characters around and spackling over rough patches in continuity. I'm looking forward to reading a Flash story that's actually a story and not just setup for the real story.

Full review here.