For gaming on a single 1920x1080 monitor on high settings, it looks fine. I have an i5-4570 and a GTX 760 for my mid-range gaming system (whole system available on my profile page) and I play The Talos Principle, the Portal series, and Team Fortress 2 mostly fine. I get some lag here and there on Portal 2 and TF2, but it can probably fixed with some more setting tweaks, it doesn't bother me too much, though. You may be able to get a nicer used GPU for the same price or less, though.
I haven't really looked into the 6th generation Intel CPUs. But, I assume it has a little more performance than last gen desktop i5 CPUs (Haswell).
As for the PSU, there are probably better options out there. I don't know too much about power supplies, it's been a while since I built my computer, but there is a professional review that seems to rate the XFX Core Edition 550W well according to their point system and conclusion (I didn't read through the entire review), my only problem was that it seems to be difficult to see exactly what PSU they are talking about. The image of the PSU of the 3rd picture on the first page seems to have the model number being XPS-550W-SEW. You probably don't need that much wattage, but, it will hopefully last a while. Also, I haven't built a micro ATX system, but they looked a bit cramped. Do you want a modular PSU?
As for the case, you may want to buy another fan if you get it. I can't comment on the airflow. But, I would personally maybe look for a case that has more fan mounts.
EDIT: Wow, maybe it is possible to get by with a non-modular PSU with a micro ATX case. I'd still be cautious, however.
EDIT (10/27/15 4:42pm): I also noticed you said you have a budget of 650-750 Euro, but your build is only ~460 Euro. Are you including peripherals (keyboard, mouse, monitor, etc) and an OS in that budget?
Edited by GameMaster, 27 October 2015 - 04:45 PM.