The Build and Finished Product
I don't really care for the look of only one of the bay covers being gone, it really does break up the design a bit. I do however think it would look fine with a pair of reservoirs, or a reservoir, fan controller, and an ODD so that all of the covers are gone. It looks much better that way, if you have to remove any at all.
If the case didn't seem all that large and roomy, think about it now with the ATX motherboard installed. It takes what are normally some large components and makes it look like a Mini-ITX build with some super short VGA - just imagine the possibilities and sheer amount of stuff you can still pack in.
The chassis fills up nicely out back, and there wasn't an issue to report. Everything went in as it is designed to do, and even the fan wire is in the right location pointing at the motherboard tray, so I did not even have to rotate that to clean up the wiring, it was already done correctly.
This is where the 800D failed pretty hard. The 900D fixes all that and offers some of the best wire management I have seen to date, and the cables are all long enough to route it super cleanly. I also like the additional plastic straps, and they even allow for the 24-pin wiring to be strapped in them. Every single wire is well managed and hidden for the most part, and I haven't even dented the near 40mm of room offered here.
The window offers a great view, even if that view includes a fair bit of the bays. Again, if at all possible, I would remove all the covers or none at all, as the DVD drive really does break up the view was once very sleek and sexy to look at.
Two things I loved when I powered up the 900D - one is the absolute silence of the four sock fans inside of the chassis, and the second is the fact that there is only a faint white LED light denoting system power. There is also the occasional flicker of the HDD activity light, again in the power button, but nothing too bold as to distract you or keep you from sleeping.