Meh, it's not that big a deal for most games. Onlive worked, albeit with a little bit of lag. Maybe not great for shooters, but for most action/puzzle/etc. games (especially controller-driven ones that don't require super precision) it was totally playable.
If your internet connection is good enough for Netflix, Onlive offered a similar experience (slightly worse, since you can't pre-buffer a game like you can a static movie) but still playable. It was a godsend when I didn't have a gaming-capable computer in college.
For $10 a month, it was a great way to try out many lesser-tier games, or for AAA games, pay $2 for a couple hours of full gameplay to see if it's something I'd like to pay full price for.
As someone who's built and played on high-end gaming PCs for the better part of two decades, streamed games are an interesting niche that I hope will open up more use cases. They are unlikely to replace mainstream desktop gaming, but maybe they can find a niche in there somewhere between mobile and consoles, both of which are already far weaker than desktop PCs but still have plenty of players and games.