Depending on many variables such as your home LAN, the player you're using, your internet service, your AV equipment, etc., etc., the video quality can be OK to very good - and the gap is closing, but it's still lacking when compared directly to BD's. The difference in sound quality of lossless codecs available for BD versus streaming from online is not even close. I, like you, have spent a pretty good amount of time, money and effort to get very good VQ and AQ in my home. I never use my TV's speakers - choosing to have the better SQ my AV system provides even when watching TV.I spent an enormous amount of time and money trying to find the ultimate perfect hi-def video and audio. It started with being in the HD-DVD camp way back when and then moving over to Blu-ray. Tweaking every little thing and never being completely satisfied. One day I just stopped. It just isn't worth the effort and when you want to watch a movie that's not in your physical library, it's available online. No waiting on it to come from Netflix. Is it as good as a Blu-ray in an OPPO? No but, "it's good enough" (actually pretty close now) and getting better everyday.
Now if we can just get a Roku (4?) that passes HD Audio so I can enjoy my Blu-rays on my server without having another box. I can dream.
'Good enough' is very subjective- and everyone has their own opinion. But for me, it's virtually never "good enough" for watching movies and concerts.
Even so, I know that convenience will eventually win. It's too bad really.