I know what you're thinking, here we go with yet another tacticool AK. But you would be wrong - the G&G GK99 is a replica of the Finnish SAKO 90 series service assault rifle. Like the Israeli Galil what you have is a Kalashnikov AK47 which has been given a bit of a make-over.
The GK99 is a beautiful and sleek looking AK variant and I personally prefer it over the Galil. Though I would be hard pressed - when it comes to authentic tactical AK variants - to chose between the GK99 and the gorgeous Real Sword Type 56-2.
As usual G&G has produced a wonderfully turned out replica, but there will be those who cringe at the thought of G&G internals. This is where a King Arms Galil and Real Sword will have the edge. But the way I look at it is that if you are an aficionado of the more niche AEGs then it is worth taking on something like a G&G and then lavishing the extra care it needs to bring it up to standard. However, that's rather putting the cart before the horse based on G&G's past performance, you never know this might be a good AEG out the box!