I've done one build in it, and I have another on order. Excellent case for the money, quieter than I thought it would be. The build I just completed was with an ATX board, it's very tight, I'll just be using this case for mATX builds in the future. The only ding I have against it is the lack of a routing hole at the top of the motherboard tray for the 8 pin. I think that the slot for the mid mounting SSD position is very clever, no screws required, and the m4 I used fit snuggly. I monitored the i3 for a couple of days, and it stayed right around 29c. Keep in mind that it doesn't come with a front fan to cool mechanical drives.
With that being said, this is my go to case for entry level builds (mATX) until something better comes along. Antec clearly stepped up to compete with Corsair, IMO, this is a better case than the 300R.