They're not quite that big, usually 20GB-30GB
Let's talk about bandwith here, blu-ray has a theoretical bandwith of 48 Mbps for a movie, but most are about 20-30 Mbps, and netflix HD says it requires 8 Mbps for HD, but they stated that 1080p HD uses 4.8 Mbps. That's an obvious difference right there. While the image may decompress to 1920x`1080, there are obvious distortions in my HD streams that shouldn't be there. Overall the quality is very good, but you can't control where there may be blips in the data speed. If you never watched a blu-ray movie, you probably wouldn't know there was a difference. However, not having to buy the movie or wait for it to show up in the mail is totally worth it for HD streaming :)
I must admit the only place I have seen Blu Ray Discs running is in a store and at a friends house on his PS3.
I don't own a BluRay player. I like the tech tho so I reckon I will "buy in", but only when the costs reduce.
Here in the UK the cheapest player I can find is 80 GBP (125 USD). I have read the reviews however and its pretty much a shocker. The better standalone players are approx 160 GBP (250 USD)
Everyone says a PS3 is the way to go but as I am not the main film watcher for the house I refuse to pay 250 GBP (399 USD) for a PS3.
Right now my households HD needs are provided by HD streaming and the (IMHO) acceptable cheat of an upscaling DVD player.
I dont know how long it will take the commercial brains at the BluRay consortium to realise that their product is ludicrously overpriced given the competitive market place, but until that day I will be waiting patiently with cash in my wallet.