I have a Black M98 custom, 13" Armson Stealth, Lapco foregrip. Lapco side bolt, double trigger, and Dye Invision Mask
It is comfortable and fits well. The straps adjust to almost any size and the modifications that can be made are amazing. It has enough pockets to hold most of the items you need. It is well padded for new players who can't stand the hit.
Nothing, except that you can't find it in any local stores and has to be ordered over the internet.
This is a great product for someone who doesn't want the usual 2+1 or 4+1or other similar items. It is easy to move in.