Considering the RV03's $140 price tag, you'd expect to lose a lot of functionality over the ~$170 full tower RV02, but that isn't necessarily true. In fact, the RV03 gains a few features not seen on previous iterations, including two USB 3.0 ports on the front panel and official support for Extended ATX motherboards. Nonetheless, its smaller frame inevitably makes things a bit trickier to work with internally.
The RV03 measures 9.25"(W) x 20.55"(H) x 22.44"(D), which is 0.91" wider, 0.75" taller and 2.87" shallower than the RV02. The Raven series has traditionally been shorter but deeper than your typical chassis as it rotates the system's guts by 90 degrees so the motherboard's I/O panel and the PSU are facing upward. It can be hard to picture, so take a look at our review of the RV02 if you're lost.
Losing nearly three inches horizontally means you'll block one of the RV03's eight expansion slots by using a 120mm "rear" exhaust fan. Likewise, two of the four 120mm front intake fans will be unusable if you occupy all of the hard drive bays while only two 180mm fans fit in the bottom of the case instead of three. In reality, those are minor limitations and probably worth the savings to most users.