Cinema is good sometimes, but it's also good being able to chill in your house with a few mates and watch films on the big screen telly with decent surround sound - allbeit without the 5.1 if downloaded (personally I don't think a lot of cinema's have good enough sound systems)..
A bit of both in my opinion, there are a lot of films I wouldn't bother/have the time to see at the cinema that I wouldn't have seen if mates hadn't downloaded them! And a lot of them are a thousand times better than the stuff I will go to the cinema for (big names like Matrix etc).
I'm never bothered about downloading a film just to watch it first though, rather wait until a decent DVD version comes out!