Just got it through the BTTF pre-order today, finished it a couple hours ago, and have to say I'm glad it came as a bonus because, DESPITE how awesome the story is, the gameplay is, and the presentation is, its all too short.
I mean, I was expecting to do more after the story ended, like some extra puzzles besides the few side ones. Compared to other $10 games, there's just better out there. I hate to make such a brutal comparison because Puzzle Agent is very unique (LOVED the mystery and intrigue, and especially the shock of the gnomes), but it's severely lacking gameplay. Don't let this pilot gather dust though! I'd like to see a sequel after BTTF! And while I might be hesitant to buy it right away without knowing it has more substance, I'd trust you guys at Telltale even if you just told me you did add more.