How DLC adds replay value, and when it feels like a scam...
Most of us view downloadable content in a positive light. Ideally, developers use DLC to extend the lifespan of their games so players don't just send those titles back into the machine as a used product. DLC can add to any game's replayability and, therefore, improve its lasting value.
Valve, Rockstar and Epic make excellent use of DLC, specifically for Team Fortress 2, Grand Theft Auto IV, and Gears of War 2. After all, even online multiplayer can get stale without new maps and such to keep things fresh.
I'm a huge proponent of DLC because some of my favorite games have the most amazing add-ons, including Team Fortress 2, BioWare's Mass Effect and Lionhead's Fable II.
In addition to a plethora of original content available in Mass Effect upon release, BioWare graced us with the amazing "Bring Down the Sky" DLC months later for a mere $5.00 or 400 Microsoft Points -- free for PC gamers. Lionhead Studios has already promised to keep Fable II alive by releasing DLC. They've kept their promise with the winter-themed "Knothole Island," priced at 800 Microsoft Points, and "See the Future" DLC, due some time this spring.
And what about even older titles like Oblivion? On April 1, Bethesda marked down all related DLC (except Horse Armor) by 50 percent, and you can bet I'm not the only one who took an interest. DLC can literally revive games most of us forgot about given all the new titles streaming onto shelves.
In such cases, DLC works a bit like expansions for PC games, extra content added after the fact. It's what most of us suspected DLC would be when it first came around for console games, but Capcom and Electronic Arts have recently rattled gamers by announcing planned DLC before their games are released.

It started with Street Fighter IV, for which Capcom announced several costume packs set to be released in the weeks after the game's launch. Seemed like a peculiar strategy at first, but they're costume add-ons so no one really raised a stink about it. The real kicker came with Resident Evil 5.
On March 12, the day before Resident Evil 5 came out, Capcom unveiled paid DLC in the form of "Versus" mode, set to arrive on Xbox LIVE and PSN just "a few weeks" after RE5 comes out. The price wasn't too steep (400 MS Points or $4.99 on PSN), but the ensuing gamer backlash was enough to warrant a couple responses from Capcom. The most notable of these is probably a forum post by Christian Svensson, in which he called all this DLC-whining complete "BS," explaining just why the hell Capcom was releasing PDLC (paid downloadable content) so soon -- separate production budgets.
Cue EA quickly chiming in with free launch-day-DLC for their upcoming Godfather II. Originally set for a February release, Godfather II was pushed back to April 7. So this "Don Control" content is free, and we're pretty sure that has something to do with all the flak Capcom got for charging for "Versus." Still, why would EA be coming out with DLC for Godfather II on the same day the game comes out? Even if the game had launched back in February, DLC in April seems awfully soon; never mind those premium upgrade packs announced for April 23 (not free).
We can't help but feel these companies are just trying to pull a fast one on gamers. Paid or free, Capcom and EA timed their DLC announcements terribly, rubbing gamers the wrong way. Whatever goes on behind their closed doors, we are given the impression that to these two companies might be handling DLC the wrong way.
Execs like Svensson can claim innocence, but many gamers will still feel cheated, wondering why the extras couldn't simply be added to the original package if they're producing both the game and DLC at the same time. For Resident Evil 5, it looks as if Capcom might have already coded the "Versus" mode into the game but ultimately decided to remove this feature and sell it back for extra profits.
With such poor timing, it's almost as if Capcom and EA are telling gamers we have to buy add-ons after purchasing the game to really get the full experience. Despite justificiation, there's a deliberate feeling of unsavory intent.
DLC is like a supplement, something that enhances a game by bringing something extra to the table, like an unexpected (yet pleasant) guest. With this new sales strategy, the add-ons feel more like the missing cake at a birthday party.

Square Enix released Final Fantasy Crystal Chronicles: My Life As King on Wii ware that had some pretty atrocious DLC at ridiculous prices. The game wasn't even that great, but if you want some extra costumes you better fork over the $$$.
I think that Rockband and Guitar Hero are the ones helping to drive the DLC market into the dirt. They seem to be leading the way with overpriced garbage. But people buy it, and other companies take note.
Honestly I have a problem with the Mirror's Edge DLC too. It's an amazing game unto itself but would feel more "full" and worth the price of admission for more people if the time trial packs were included, or alternately if the game was priced 10 bucks cheaper and the DLC released to fill in the gap when ready. I mean..60 bucks is a lot for a (roughly) 10 hour game, though damn it's fun to replay..
Agree with kik..as always, vote with your wallet. It's as much our fault as it is theirs. Still, its unfortunate how many developers turn out to be more capitalist than people who just love games and want to make a decent living making them (there is a difference).