I haven't seen any reviews for the Pure Flow 5 (PF5), so I'm going to write one. *Stipulations about me after review.
Summary: I like it a lot.
Background: I used the first two PFs but stopped after the redesigned midsole/outsole on the PF3. It felt divided length-wise into two pieces, causing me to roll out on landing in an uncomfortable way. Skipped the PF4 entirely.
First Impressions: The PF5 looks a lot different from prior models. I was worried at first because the midsole/outsole resembles the short-lived Pure Drift. The minimalist Pure Drift had length-wise spines of hard foam with large gaps between. I suppose they were designed to match your metatarsals and distribute weight evenly. That didn't work out for me, as I landed on only one of the spines, leading to an uncomfortable pressure point. Perhaps others had the same experience - as far as I know it only lasted one cycle. I was worried this would happen here, but Brooks seems to have solved this issue.
Running: At least on my foot, the PF5 feels very similar to prior versions. Arch is about the same, foot hits the ground about the same. It reportedly has a 4mm drop but feels like less - as opposed to, say, the Kinvara, which reportedly has 4 but feels like it has more than the Pegasus, which has 10.
A few things are different. The foam feels softer but somehow bouncier. Maybe the softness makes the spines blend together instead of causing hot spots. The upper feels much narrower and is actually tight against the top of my foot. Not a problem for me because I have narrow, low volume feet.
The "bounciness" is what I particularly like about this update. I always really liked how the PF felt on easy runs but never did anything uptempo in them. I may not give up my Streak LTs, but I think I will consider these for long tempo runs.
*I am an office worker generally in 32-33 min 10k shape. I tried these shoes during one week of maintenance runs at 6:00 to 7:30 pace. I have a skinny, low arch foot, land on mid foot, and generally hate high heel drop shoes. For some reason I ran quite happily in the Pegasus for most of last year.