first off I have not seen many commercial flow meters that are anything other than visual... If you mean there is no meter that I agree. The aluminum is a big downside. Also I'm worried about that acrylic cover they are using as its prone to cracking. Waste of money IMHO.
Also zip22 if you are gonna bash a review at least read all of it mainly this "Overall I feel that this product is worth 5 out of 5 and our editors choice award for a great product that makes it easier to have control over your watercooling rig. "