It took me way too long to pull the trigger on Inside. Limbo was one of my favorite games of all time. I wasn't sure about Inside. When you watch part of a playthrough it doesn't look like there's a lot going on and that it's just another game going for the "experience". Well yes it is, but what you don't get from watching it is just how connected the game makes you feel to the character. I didn't realize there was a demo until right now, so just go play the demo, why am I even trying to explain it.
And since I recommended it I played through Roundabout three times... The feeling of progress is fantastic. The first time you feel like a complete idiot, the second time you kinda get the hang of it, and after that you're getting hooked on the speedrun mode. It's a fantastic game.