From a design perspective, it appears the story missions are to introduce the new tools/weapons and the new characters. There are practically no barriers to completing these, except the 6-7 life limit on each level. Making the game appear short as you stumble through each level, respawning at a spot very close to where you die.
But the side quests, and stickering secret areas, both are more challenging and expect players to come back with objects they've found from other stages ... I'm assuming some of the challenges will be easier if you complete the game like the Angry Bear task if you have the
?
We'll see though, as I'm assuming this without completing the side quests, if it still feels short I'll be a bit annoyed ... but I'm lucky as I haven't played user-made levels from 1 or 2.