Single player games i'd probably get on Impluse as i want them to be successful and grow in order for Steam to get better as currently there's no equivalent Steam competition....

Multiplayer? It depends on the game but atm there's not much difference between me playing on Steam or Impluse with regards to people i know.

Impulse doesn't require, typically, that Impulse itself be running for your games to work. You don't seem to have to call a central server to ask permission to run a game; once it's installed, you can just run it.

So I prefer it to Steam when I have the option.

I greatly prefer Steam. Part of this is that I prefer to have everything in one place and Steam just got headway into my life first. However, I have bought tons of stuff off Steam and they've been flawless transactions every time. Meanwhile, I have only bought three games off Impulse and each time I've suffered through annoying issues, so other then possibly Elemental or other Stardock-published games I don't plan on buying anything from their service again.

That aside, personally, I don't find Impulse's community features or interface to be as pleasant as Steam but there's nothing specifically wrong with them.

None of this matters though, because Impulse has already altered their prices to match the exchange rate of my country. For example, Resident Evil 5 is $50 at my local retailer and on Steam and most of their other competitors, but on Impulse it's $54.34. That may be the fair thing to do and partially out of their control, but the fact remains that for Canada at least, the price never is the same anymore, barring a significant sale price.

Personally, my preference is in the following order: Steam, Direct2Drive, GamersGate, Impulse, Retail Store, stealing it from a truck, donating my body for science, the EA Store.

Well honestly I like the client for Impulse better than Steam's.

The problem is that Steam is so convenient and has so much market penetration. The weekend deals quickly built a pile of Steam on my hard drive that I now have to go through. I have about 8 or 9 games on Impulse. I think Impulse needs to offer the same type of weekend deals to get people interested in the client. If they were more aggressive in going after market share I think they'd be more popular right now.

I've only tried Steam. I'm tempted to try one of the other services, specifically D2D with their ongoing sale. I've even decided that I'm going to use D2-- and then I don't. If the same games were on Steam for the price they've been on sale at D2D I would have made several purchases. For me it is all about consolidation of only having to think about a single service-- as well as the community aspect of being able to be invited to a L4D match even f I'm on another game I purchased from Steam.

Pretty much this. For me the only gripe I have is the region locking that sometimes happens on Steam. Hmm, to be honest, once locked out on Steam, I've never actually gone to the others to see if it was the same there. If they were offering the same game that is.

I've only ever used Steam and GoG. So far my experience with both has been nothing but positive. The free copy of Beneath a Steel Sky I got off of GoG helped satisfy the adventure game lust that was left over after finishing Monkey Island SE.

I do intend on getting Sins of a Solar Empire off Impulse one of these days. But until then I'm content w/ Steam.

Well, Steam got in first so is my preferred service. If something is available on there for the same price as everywhere else, that's where I'll go. I'm very much invested in it and the community features. I have used GamersGate and Direct2Drive and both are pretty good for getting the odd game they have cheaper. I've stayed away from Impulse as I'm not keen on having more than one client-based service and I've never felt the need to use it: until something essential turns up on there that I can't get elsewhere or is majorly discounted compared to elsewhere, I can't really see myself using it either. Just my 2p.

I find Impulse to be less annoying and intrusive than Steam. But as others already mentioned Steam defined the market and therefore holds the most prominent place. In a year or two Impulse should be able to catch up to the nicer aspects of Steam and then I will probably prefer it to Steam. Ideally Steam would allow API access to its data like Facebook, so you can export your friend's list into other applications.

I've started using D2D only recently. Haven't had any issues with it, but I'm not really big on it. The interface is really untrustworthy and the downloader is confusing at best (when it comes to its functionality).

Haven't used any other services yet. And unlike kuddles, I wouldn't touch EAStore even if my body parts have been donated to science. There is just no justification that could make me give money to EAStore. Period. If that is the only place in the world a game could be gotten, then it's not a game worth playing. By definition.

--Edit--

This is one thing that actually bothers me a bit about Impulse. I wish there was a switch where I can choose which currency the prices are displayed in.

If it's only a matter of seeing all of your games, you can add non-Steam games to your Steam list. Regardless of where they came from. Steam won't be able to update them and such, but you'll have them all in the same list.

The way it's supposed to work (I think) is that offline only works for 3-4 days before you have to re-validate. That's good enough for me, but I do prefer Impulses (and GOG) hands off style.

I have heard a lot of different things from different people. Maybe it's a very nitpicky functionality, or changes from game to game?

What I meant was I like to see all the games I OWN in one place, not all the games I have installed.
I could see myself, 3 years from now, thinking - "I want to replay Bioshock - where did I buy that from again?" - and having to go through 4 different sites looking for it. That's what's annoying.

Which reminds me of another thing Impulse needs to fix: I have to run the Impulse client to download and install the game anyways, as well as enter my username, why do I first have to manually input my serial key sent to me seperately then? A minor niggle, I admit, but still...

I see. I'm sorry I misunderstood what you mean.

I don't recall ever having to do that on Impulse. But I do recall having to do it on Steam.

I love Steam and have never had a problem with offline mode. When I'm playing Left 4 Dead my wife might want to play Plants vs Zombies so she disconnects her internet connection and starts up steam in offline mode. I've never seen it require a connection after a set number of days either.