Even though the Zalman HD135 HTPC Case has a few flaws I still like it a lot. Zalman has designed it to accommodate standard components which is a big plus, yet it is rather low profile with a total height of only 13.5 cm.
The airflow concept is well thought out which means I see it well possible that you run a multi GPU solution in the case. Since it works without the need of slot riser cards you can install as many add-in cards as in a regular case.
Being able to mount a standard sized optical drive is a great plus because you can save a good amount of money here compared to using notebook drives. Unfortunately there are some issues when using the case without optical drive.
Overall I would say if you are looking for a beautiful media PC case with great potential for expandability and are willing to work around the problems, you have found pretty much the ideal case. I would suggest getting the silver version to avoid having fingerprints all over the case.