No, I'm not talking about the endings. Well, not just about the endings.
As we all know by now, The Walking Dead pretty much forces you on one path when it comes to the plot. There's no way of changing how things end, and the circumstances play out no matter what choices you make.
Without getting into too much spoiler territory, the Mass Effect series is kinda the same way. You think you'll be making some big decisions that'll effect the outcome of the story, but that isn't really the case.
I believe the big issue is how the stories are set up. Halfway through TWD, we've got a good feeling where it'll end. In ME, we think we can DO THE IMPOSSIBLE. OUR WAY.
I get into much more detail in this post here: http://kambyero.com/2013/03/03/why_decisions_dont_matter_1/
Lots of spoilers for both the Mass Effect series and The Walking Dead, obviously.