First - nice work. Impulse has come a long way, baby. And in very little time, so it will be very cool to see what it looks like in a year.
Second - What has made Steam so successful in the longterm, imo, is not only the extensive library of games but the ability of Valve to create a society. It's the gamer's Myspace, and the ability to connect with friends and communities, to be social, will give it brand longevity where a DDL service with far superior backend and gadgets but limited social dynamics would fail.
If you want to position yourself as a comparative Facebook longterm you will need to incorporate the type of community networking that goes far beyond what is currently available. Player groups, blogs, supported ventrilo and teamspeak servers (and later native VoIP), clans, achievements, extremely customizable user profiles, player reviews, stats, and rankings. "You like this game? Maybe you'll like these others."
And to extend the metaphor - Yes, it's completely ridiculous for people to complain that Facebook doesn't just operate within the Myspace UI..
Third - as an uninformed outsider this is what I'd be concentrating on -
- get more games on Impulse faster. (the catalog is there and it's a pipeline issue?)
- visit the XBLA model as well as the Steam one - how many Indy, vintage, or casual games are on Impulse? That's a huge demographic that no one seems to be touching...Hook up with Armor or Popcap Games, for example, and you've brought in simple games that get millions and millions of plays.
- make the multiplayer tracking and play very, very smooth right out of the gate
- make and advertise other deals - weekend sales are great, but it would be cool to see "buy any 3 titles for over $15.00 ea and get $5 off" for example
- Don't get bitter. Right now Steam is 2006 Google and can do no wrong, as well as having, what, 90% of the market? A year ago that was probably more like 99%. The thing is, there is no one else in the market right now but you and them, so keep working hard, stay hungry, and polish the crap out of your program and you will be really nicely positioned when they stumble...