The 750D's Tradeoffs
There are some caveats to be aware of in the 750D as compared to some of Corsair's other product lines. Specifically, the Corsair 750D lacks the Corsair 650D's fan controller, top-mounted slot for a 3.5" HDD, or the sound-deadening foam built into the Corsair 550D.
How much you like the case may also depend on your PSU. The shorter and more modular the unit, the better chance you'll be able to take full advantage of the available internal space and routing points. A 750W PC Power & Cooling unit can only use one of the two cut-outs, and has to run a significant amount of cable through the far right-hand space. Users with different power supplies won't have an issue, however, even if the unit is longer but uses modular cabling. Also note that drive cages can stack from the bottom (you can put the third unit on top of the second), but not from the top. Neither drive cage will attach to the bottom of the 5.25-inch bays.
What Corsair has done is prioritize radiator space above virtually any other features. If you're a serious enthusiast, and you wanted a case that encompasses some of the features on the 900D but at a much lower price point, than the 750D is going to make you a very happy camper. Customers who want something with broader appeal beyond monstrous water-cooling setups, however, may want to look elsewhere.