IMO it would look stupider to have light shining on your HT screen than to have curtains with blinds.
Seriously, I've seen a mix of the two before, but usually with those blinds I've only seen "modest" window treatments -- some type of valance and a swag, for example. Still, fashions change quickly...be on the leading edge and start a trend! Unless you're very self-conscious and worried about what the neighbors might think, I can't see any real downside to just throwing some complementary curtains over those blinds. You don't want to compromise your HT experience, which you've likely invested far more money in than in your blinds.