THIS is exactly the amount of game length that I was expecting for an "episode". Sure, anyone can gripe that it could be longer/harder but given the monthly releases this episode definitely hit the "sweet spot".
The puzzles were more intertwined and there was more room for you to have to rationally think about what to do next (as opposed to basically being directly told what to do).
Episode 1 had a decent length due to all the exploring of mundane items and the whole "newness" factor. Episode 2 was definitely shorter due to the recycled locations and comments (thus less exploration) and Episode 3 was...well...pretty darn short.
Episode 3 left me cold due to length and I was starting to get concerned if all future episodes would be brief encounters.
But, Episode 4 has restored all my hope and my 2.5 - 3 hours playing it left me entirely satisfied and quite eager to play the next one.
I didn't even mind the "walking back and forth" bits because it meant that you had to know what you were planning to do next as opposed to having the next step staring at you in the face.
I'm very happy (and relieved) by this episode and...well, I'm just pleased all around.
In the end, buying a 2 to 3 hour game for $9 (if you were to buy this as a single episode) is a good deal compared to a 1.5 hour movie for $20 and...I WANT MORE!!!