Some reviews of Flash: Rebirth #6 that I’ve found around the internet:

Multiversity Comics – “very well illustrated one by Van Sciver…but I’m not going to lie, I found Barry Allen’s overall return and the expansion of his relationship with the Speed Force to not be a very satisfactory story overall. ”

Robot 6: Grumpy Old Fan – “Flash: Rebirth may read better as the first installment in an extended saga, but it risks alienating readers expecting a little more immediate follow-through.”

Comic Book Revolution – “I am just glad that this story is over so we can move onto the new Flash monthly title. Despite all the problems with Flash: Rebirth, I still remain extremely confident that Johns is going to crank out a quality read with the new Flash monthly titles.”

IGN – “The final issue, despite its flaws, provided a fitting close to the character’s journey here while still teasing at what’s to come.”

Newsarama Best Shots Rapid Reviews – “a lackluster final issue that comes off as more lightswitch rave than lightning storm”

Airship Over Water – “if you’ve been reading this series thus far, you really should pick up this issue to complete the story. It’s worth it.”

X-Man’s Comic Blog – “With the exception of the Final Crisis debacle, I’ve never been more disappointed in DC.”

Every Day Is Like Wednesday – “If you’re reading this series just to see how Barry Allen returns or to keep abreast of the big events in the DCU, this issue is surprisingly, entirely skip-able.”

Comicsbulletin – “The story and ideas presented throughout the first five issues of Flash: Rebirth were all over the place, so it should come as no surprise that the sixth and final chapter is the same way.”

Comic Reviews by Walt – “As a whole, this issue’s quite a disappointment, a lukewarm ending to what should’ve been a hot series.”

Pai Wings – “So after reading this, I feel ready for a Flash book dedicated to Barry.”

Flash-Back Podcast (audio)

ComicVine (video)

And of course there’s Speed Force’s review as well.