You buy a APU for the excellent integrated graphics.
But, there are no real good upgrades, particularly for a gamer.
If you install a superior discrete graphics card, you will have thrown away the big advantage of the APU.
Then, you are left with a relatively weak cpu. Most games depend on only a few fast cores.
The possible upgrades are to more cores, but few games will use more than 2-3 cores so 6+ cores are not very helpful.
Bottom line.....
What you get with a APU is what you will live with forever.
Here is a set of tests which includes some APU processors with different graphics cards:
http://www.anandtech.com/show/10543/the-skylake-core-i3-51w-cpu-review-i3-6320-6300-6100-tested