Downloading games is convenient, but the fact that you don't receive physical media isn't always reflected in the pricing. Over at our sister site Kotaku, David has revisited the issue of the Xbox Games On Demand platform, to see if downloads for that platform offer better value than they did at launch.
David ran an assessment of the launch pricing for Games On Demand back in August and concluded that the prices were "crazy". Nine months on, the differential isn't so great, but the Kotaku conclusion is that online buying isn't often going to yield big price benefits:
It’s clear that in many cases you’re still getting a superior deal at retail. The prevalence of discounted prices in the list below indicates how much more flexible retailers are when it comes to lowering price points. Add in the further options afforded by the preowned market, price matching and Classics range, not to mention the bandwidth costs of downloading to your overpriced 360 hard drive, and it looks even less attractive to conduct your shopping online.
With that said, as David notes, having another purchasing option is better than a restricted range of retailers. Hit the full post to see if a game you fancy for your Xbox stacks up as an on-demand title.