[iShoot]

This is one of our newest products. It's one of the first I've seen that has a side-charging handle that doesn't move back and forth while shooting. I like that because you don't have to worry about the handle hitting anything (post, tree, arm, hand, whatever) and possibly stopping motion of the bolt.
There's a few other non-reciprocating uppers out there. They're all a bit pricey. This one has a dust cover and forward assist which sets it apart from most of the others.
It can also be used with any standard bcg, no special conversion needed.

Non-Reciprocating Side Charging Billet Ar15 Upper with DCFA

 

[phillipd]

Interesting. I like that.

 

[Enterprise65]

As mentioned, it's pricey. It's three times more expensive than a standard upper. While I like the concept and innovation, it's not something I could justify.

 

[Hoot G]

I started using side chargers when I built my first (and 2nd, and 3rd) 300 BO and I'm having a really hard time using the tail puller any more. YMMV, but that's my experience.