Yeah they are huge, and feel kind of cheap compared to the solid hunk of technology that is the CoreGafx. The plastic seems to be the same but the fact that it's mostly empty makes to feel light and a bit flimsy me, it makes hollow noises when you move it, and the card port door is really cheap feeling, although they are quite cool in a weird way. And if you add the memory unit to the back the extra bit of heft makes it feel a bit more subtantial in your hand though.
As a PCE collector it's worth owning but I can kinda see why these didn't catch on. They just don't ooze quality like any other piece of NEC hardware does and it's a weird design over all.