In the aspect of just being a chassis capable of running Mini-ITX based systems, it is one of the longest we have seen, but there is more than enough room for all of your components to make a tiny motherboard based power house. With just one fan pumping air out of the back of the chassis, the PSU pumping out the front of the chassis, and the sides allowing for passive airflow to creep in and get pulled by the rear exhaust fan, thermals inside of the chassis are very reasonable for the way the chassis is delivered. We could have also added some fans to the right side of the chassis to elevate the cooling efficiency and still used the same components. We just would have moved the drive to the floor of the chassis and removed the support to allow room for them there. There is the one sticking point about the expansion slots, but with some force and a bit of struggling, I was able to eventually get my card secured into the 915F, but it was much more work than it should have been to mount my video card.
Then there is the whole other aspect of what this chassis will do. Even with the front bay still in place, and with room for a smaller PSU like the one we used for this build, there is room for a pair of radiators, one on either side. You can use the PSU to power pumps and lighting, have plenty of room in the middle of the chassis for a tube reservoir, pumps, fan headers, and excess wiring all to go in and stay tidy when it's built. While it is entirely possible to house thick radiators with fans on both sides, you do limit the space in the middle for other components, but the large grommet at the back and the smaller ones in the middle allow you to set up any sort of configuration of 140mm and 120mm based radiators. While the HAF Stacker 915F is intended to be used with the rest of the HAF Stacker components, I see no reason why you can't be a bit creative and use this with any chassis that is nine inches wide and near 23 inches deep.
As a standalone SFF chassis that can also be used to support additional water cooling to almost any other chassis where external water cooling is your only option left, the fact that this chassis is going to sell at $69.99 is great value to be had in my opinion. Having the ability to stack two or three of these high could make an office setup like mine much cleaner than my two main rigs and a laptop all spread across the room. With a design like this, you have one central location for many systems, and at a glance, you can see if the entire array is running and doing what they should be doing. Then of course you can add this to the HAF Stacker 935 for even more space for whatever you desire, is a handy feature as well.
I really think that Cooler Master did a great job on the HAF Stacker 915F as a standalone M-ITX based chassis, and in the review of the HAF Stacker 935 that will go online soon, you will see how it plays into that design as well. As long as you are aware of the expansion slot struggle and are willing to try your hand with it, I don't see why you would pass up on this design, where you can get bored with it one way, and completely readdress the design and still have a pedestal on hand. With just a tiny bit of modding, I want to turn this into a portable water cooling kit that I can just have a pair of quick disconnects and use this for benching purposes next to my open air test rig - the options are truly only limited to your imagination with the HAF Stacker 915F.