To like or not to like?
(Disclaimer: if Tux Racer sets your loins afire, I am obviously talking out of my nethers from your viewpoint).
On one hand having Steam in the picture would allow porting of real, big-money, games. It would solve the distribution problem (no one carried Linux games in the early 2000s, when there was, briefly, an interest in Linux as a gaming platform).
It would solve piracy problems - the tight leash Steam puts on a game would probably not be crackable by most and a well-designed system would allow for occasional cracks and disabling some functionality games that are running on exploits. Then the usual patch-crack cycles would happen, but many people would just... pay.
Which is... good. If you are deluded enough to believe that a game studio who spent millions of dollars developing a game may deserve payment from its players. I am that kind of delusional person.
On the other hand, I have a licensed Shogun 2 running under Bootcamp on my Mac. After working for 3 months, Steam stopped working. The troubleshooting instructions for lost Steam connectivity looks like they were written up by a dyslexic C++ coder after a Red Bull binge on his personal blog.
"Have you tried turning it off and on again?"
Nothing remotely user-friendly to allow me to use my $60 game.
And... Steam _always_ wants a call home. Even on a single-user game. How about allowing for non-connected solo play? Steam complaints are usually front and center of many game reviews.
On balance, I'll go with a cautious happy icon.