Granted, both The Walking Dead and Wolf Among Us are incredible games. I thoroughly enjoy both of them. That being said....there are things about them that can be improved for future projects you work on.
1) Choices. Those big choices that you display at the end of the episode? Actually give us some consequences and branching stories. Obviously you have a story to tell and we understand that, but you can still do that effectively while giving the player agency. Look at how games such as The Witcher does it. Those games have a very satisfying story, but even more satisfying are the choices and the way they effect the plot.
2) Dialogue. (?) Somebody will remember that.... Prove it! Actually give us some dialogue trees. Make characters act different to us based on what we say. Make scenes play out differently. You guys have said it yourself that dialogue is considered the gameplay in these episodes, so try to expand on it and have these dialogue trees actually meaningful.
3) Determinant characters. The Walking Dead especially is guilty of this. Any character the player tries to save either ends up dead later on anyway or irrelevant to the plot from that point on. Sometimes both. Why give us the option to save someone if they will be entirely irrelevant to the plot from that point on? If you give us determinant characters and you intend to kill them off later anyway, at least reward us for saving them by giving us some additional conversations with them, giving them some more character development, and if possible having them change some aspect of the plot that would have been without them.
4) Episode length. I'm not going to say "make episodes longer" - what I'm going to say is make episodes the length they are supposed to be to tell the story. With TWD S2 especially lately, it feels like Telltale had so many brilliant ideas for the story and plot of the episode but rushed the telling of the tale. Faster pacing isn't necessarily a bad thing when the characters are likable or interesting and they don't fall behind the plot, but rather run with it. 400 Days and Wolf Ep 1 were great here. 400 Days was 90 minutes if I recall correctly, and Faith was 2 hours. Many characters in 400 Days were instant classics that were genuinely interesting, despite the length of their chapters. I was impressed with Telltale's ability to develop them in such a small amount of time. Faith had a really, really good plotline with twists and turns but ultimately it did what 400 Days did so good and that was character development.
Subsequent episodes of WAU and TWDS2 have been (for the most part) lacking in the character development because they have had to keep up with their plot within a limited amount of time. What I'm basically saying is find the right balance between plot and character development and don't worry too much about the episode's length, just focus on telling the best story. The length will be what it is.
I'm sure that Borderlands will be awesome. TWD and WAU are awesome too. But these flaws make them less awesome. With still time to develop Borderlands and Game of Thrones before release, I hope Telltale is able to use this criticism to make their future projects even more awesome.