First impressions of the rifle are good; solid G&G build, full metal upper and lower receiver and an okay plastic grip and hand guard. The SOPMOD stock looks great and is extremely comfortable when shouldering the weapon, and the supplied adjustable iron sights are fine.
This is the Gen 3 version of the weapon, fitted with a MOSFET, which gives a quick, snappy trigger response, and the pneumatic blowback is a nice addition.
A couple of negatives; the hand guard isn't the most comfortable, but can easily be swapped out for a quad rail, although battery space is a bit tight, and on my version, the dust cover will not stay closed. Not a massive deal but slightly annoying.
Overall, I'd say this is a good mid-level M4 platform, providing a great base to build on (already got my eye on a suppressor and quad rail) and I'm looking forward to getting it out in the field,
Just beware when comparing on other sites, as other retailers are advertising the CQB-H cheaper at first glance, but they're the old Gen 2 version without the MOSFET, and cheaper internals.
Final word about the service from Zero One; awesome. Weapon ordered 10pm on Monday, delivered before noon on Wednesday using the regular Royal Mail delivery. Can't complain at that.