Only someone who has bought or handles this case will be able to tell you some of these things. Cases are personal preference a lot of times. Someone may think it's the best thing since sliced bread and another person may say it's a POS. I suggest reading a bunch or review and see for yourself. I always ready the Newegg reviews. Apparently it is well liked though. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Also, as far as your technical questions:
- Yes it will handle 2 GTX670's. Most any Mid size case will have no issues.
- The airflow looks good. It comes with a rear (a must) and a side fan. The side fan is a good idea when having dual cards as it circulates the hot pocket of air that forms between the two cards. It does not have an intake fan, but you could add one if you like.
- Build quality will be a preference, but the price range it is in is typically decent for a modest built. You don't get outstanding build quality until you get to the $150-$200 price range when the cases are very ridged.
- Who cares if the inside is painted. It's a preference
- For any modest build you only really need a rear exhaust fan. The side fan is a nice option for dual cards, and the intake doesn't really do much for you in most scenarios. Though, you can always move the side fan to the front intake.
- It supports ATX, micro atx, baby AT http://www.nzxt.com/new/products/crafted_series/apollo
- Cases are personal preference.
op asked "is this a good one" lets face it, its not. It is very low end. my answer was not directed at you, its just my opinion.
when i see a case like this i worry about hard drive temps, most hard drive makers list max operating temp at around 60 c. With no air flow on that end of a case with one 670 maybe two, seems like the hdd would be the point of failure.
- I say compared to other cases in it's price range it is a typical case. According to 931 reviews on Newegg it has an average of 5 eggs. A few people thinks it's quite nice. It's all preference. It also has $20 right now.
- I don't understand the hard drive concerns. A single drive or two drives spaced will be perfectly fine. With an exhaust fan it will create negative air pressure that will cause air to be pulled in from the open vents in the case. As mentioned, you can alway move the side fan to the front position. With a single video card that is probably the better placement. Or just buy a 3rd fan.