The great thing about Down-Loadable Content is it's far cheaper than full games. Map packs and expantions add to games with content that helps extend it's story, gameplay, or both. I often get games for about $10~$20 below retail (with the use of the internet, of course) so I willingly buy extra content without really feeling like I'm spending more.

AS FOR DLC GAMES, after Shadow Complex and Battlefield 1943 (or before, but those are my favorites) DLC games are easily a better "bang for your buck" than most retail games.
Steam goes so far as to sell ENTIRE RETAIL GAMES FOR DOWNLOAD AT A LOWER PRICE. Xbox live has caught on to this and is doing the same, however they persist on mostly selling older games, and Steam still has a wider selection (and the best modding comunity ever) than Live.
Posting due to bored-ness. I has Xbox360 gamertag, Zdonick. Only people I remove are people who go offline for over 2 months or swear, are under 12, yell always, and talk smack and lose (followed by claims of hacks or more swears).