Not quite on par with 'Curious Village', but still well worth your time.
I think it's mainly down to two points. Firstly, a sense of 'been there, done that, got the t-shirt' from the first one. A lot of puzzles seemed to be variations or re-hashes of puzzles from Curious Village. The other thing is (POSSIBLE SPOILER ALERT) that the story is also in some ways quite similar to the first one, particularly the main twist. It was also a fairly illogical one (CERTAIN SPOILER ALERT: even more so than the robot people of the Curious Village). This was somewhat made up for by the emotional ending.
Having said that, you're still in for a satisfying ride here, with plenty of plot twists and shifty shenanigans. Old foes & friends return, along with a new cast of extras, all cleverly animated and with entertaining dialogue. The whole thing looks and sounds a treat, and we are even treated to some first rate voice acting in dialogue sequences. Nice!
The extras are the best part of Diabolical Box. This time around we can exercise a hamster to make it lose weight, brew a variety of suspicious teas for strangers, reassemble a camera to take pics which then can be assessed in a game of 'spot the difference', and more. These certainly help to break up the monotony of the 138 puzzles you must solve in the game. Well, actually you only need to solve 80 I think to finish the story mode, but there's plenty to come back to when you're done, including a host of unlocks.
Basically, if you enjoyed the first one, you'll enjoy this one, but I just found that this time around that whole feeling of 'wow, this is clever' had trailed off a little, and solving the huge amount of puzzles bacame slightly monotonous later on. Apart from that and what I consider a lame twist, it was still a great experience. The characters alone will put a smile on your face once more.
I'll definitely be following this series, especially now that it's making it's way to the 3DS.