I've used the full-tower Transformer they are well-built.
That one looks familiar... Hmm compare to the COOLER MASTER Centurion 532
almost identical save the core fan mounting bracket. Based on that, the 532 is a good quality case so that Sunbeam should be as well. If you don't like the window consider the 532 it is well-cooled even has the same side panel fan capability and without the window is much easier to mod a fan in the lower vent as well.