I will start off saying that this is a major upgrade to a previous build, different enough to say it is a different computer. I use it for gaming, mostly FPS's like BF3/4, Planetside 2, Half-life, Space Engineers, KSP. Here is a breakdown of what I think of each part:
CPU: I have to say, going from an AMD Phenom II 965 to this is a large change for the better. Everything runs a little smoother, nothing freezes. It also puts out a lot less heat, hardly hits 38C under full load. Also proves that you don't need a 4.5Ghz overclocked 3570k for gaming, this works very good.
CPU Cooler: Again, this cooler works wonders. If you have the space for it, get it. Even without the fan, it dissipates enough heat to run basic programs. I had to turn it sideways to fit in this case, but it still works.
Motherboard: So far (after 1 week), it is just as good and even better than my other ASRock. It has decent avalable programs for CPU tuning, fan control, a nice UEFI BIOS, and such. It only has 2 fan slots, which are located in the middle-back of the board, which is a little hard to make clean wiring. Everything else is good, it has a USB 3.0 header, supports PCI-E 3.0, has 2 RAM slots. The only major problem I had was the cpu socket location, it limited how I could install the EVO. A pre-sealed liquid cooler would be best for the case.
RAM: Not much to say, got it used from a friend, runs at 1600Mhz, and works good as far as I know. It is low profile, which is a must-have for any compact system.
SSD: I upgraded to this after being annoyed at slow application startup times. A huge difference, another must-have for anyone who does more than web browsing. Just make sure to get it much larger than you need. I currently use it for my major games, as well as major apps.
HDD: In my opinion the best 1TB budget drive you could get. It is decently fast and has not caused me problems.
GPU: A lot of people might give me hell for this, but let me explain. It was on sale a while back for 115, and I upgraded it from a 7750. I plan to sell it as a part of a future build, or use it for a budget gaming system. Back to the performance of it, its amazing for what I use it for. With the i5, I can play BF3 at 60fps on ultra, as well as BF4 on ultra around 30-40fps (Not what I play at, but still looks great). My other major game, Planetside 2, plays great with my i5 and 650ti boost, with the new update it runs about 50fps stable, on the same settings of my other computer, which was about 30-40fps stable. Needless to say, if you wan't to stay on a budget and play the best games, look at this card. One thing I would do differently would have been to get the 2GB VRAM model, for SLI-Capability and added performance. (This card is benchmarked to add about 80-100% more FPS).
Case: My second case, coming from a mid-ATX, this is a little different. It feels "fat", and shorter than my Raidmax Stingray. It is NOT a tiny case, and it is as heavy as any other case. I transport it about once a week, and highly appropriate the handles. The feet are a little wobbly, but is not bad. One of the things that bugs me is the front fan grill, the way the second 120mm fan mount is in place makes you remove the drive bay. The side panels are a little bad too, they sometimes get stuck when trying to pull them out. Also, one of the front pins that snaps the grill onto the case broke, but does not create a huge problem. I plan to mount a 1 or 2 fan pre-sealed radiator in the front or top, depending on when they go on sale (New years?). If you are more interested in the case, feel free to ask. I will try to answer any questions.
Fans: Loud. Just, loud. Even using the 7V adapter, they spin at over 2000 RPM. When they are at 5V, they hardly push air. If you are looking for a fan like this, get the quiet versions. They work great though and push a lot of air if you do not care about the noise. Can not be controlled by my motherboards, not sure if it works on others. Has a 3-pin connector.
Power supply: Lastly, the most important part of the system. It has been going strong for a whole year with not one problem. It has all the cables I need at least, but modular would be better in the mini-itx case.
So that's it! Thanks for taking the time to read, or skip right to this part. If you have any questions, please feel free to ask. And if you have suggestions on future upgrades, I would appreciate that as well :)