No outstanding issues here.
I bought my G36 a couple years ago new. Only problem I ever encountered was when I added a +1 mag extension. This increases the space that the mag spring has to expand, thus slightly weakening its force on the follower.
Laymen's terms it doesn't push up on the loaded rounds as hard which alters the timing of the mechanics of stripping, feeding and ejecting of rounds just ever-so slightly. -But just enough to cause a FTE once in a while.
This only caused a few fail-to-ejects, but that was enough for me to be concerned about life-saving reliability.
So, I installed Wolff mag springs on the mags that had extensions and I haven't had a problem, one, since.
If you install a +0 extension, you will not change the functioning of the mag at all and should not have any issues.
Other than that, if you keep it box stock, it runs like a clock.
Mine feeds everything I've ever run through it and begs for more.
Accurate, reliable and easy as pie to conceal.
This occurred and was solved within the first 200 rounds.
2000 rounds later it still works like a charm.
Best CCW ever all things considered.