The Antec Fusion Remote is a micro-ATX HTPC case, so naturally the interior room is tight. However, the layout of the Antec Fusion Remote is quite robust. There are two 80mm fan mounts on the right side of the case which provide all of the case's cooling. These fans exhaust air directly away from the motherboard and processor. The hard drives, mounted at the front of the case are directly in the front of the intake vents to ensure they receive ventilation. The power supply, on the other hand, is kept in its own compartment on the left side of the case.
All of this does keep the Fusion Remote cool, although to be honest that is hardly surprising. HTPCs aren't exactly behemoths, and one could very nearly place an HTPC inside a space heater and experience reasonable operating temperatures. The real reason to like this cooling setup is that it decreases the amount of ventilation holes in the case, and this results in a case which is quieter than many of its competitors.
In terms of capacity, the case provides about what one would expect. There is room for one optical drive, two internal hard drives, a mATX motherboard, slim PCI cards, and any power supply which isn't a monster. This is all fairly typical stuff for an HTPC, as is the front layout of two USB and the typical headphone and microphone jacks. One included feature which isn't common on HTPCs is the front firewire port, which is located right next to the USB ports.