To me they're like Kickstarter, something which initially looked very exciting but over time has shown itself to be a cardboard cut-out with nothing behind it.
The concept of games being released on physical is great, but the mechanism for reserving a game (be there and hope) is poor for consumers. In addition to that, the actual games themselves are more often than not little more than flash games which can be played online free. There is the occasional gem, but instead of actually delivering titles like Castle Crashers or the like, we're getting any old thing they can convince the creator to slap onto a disc.
Pricing's another problem - you've got these substandard games which cost more than you could buy a better game released via a standard publisher which has gone down in price a few weeks after release. Postage costs make this so much worse - Limited Run charge $15 to get a game to me in Europe - it seriously bumps up the investment needed to secure one.
I order occasionally, but only very occasionally, far too much dross - the interesting games (like Bomber Crew) tend to go with specialist or budget publishers rather than the limited ones.