The one very important functionality (at least for me) missing that was in construct classic, is "pick by comparison" where you could pick a sprite by comparing its... whatever, say instance variable.
For anyone wondering how to achieve that now (not a very good way to do this, but as far as i know, the only way, so @Ashley goes the question is there any other, more optimal way, or is there a chance to add this functionality) is to create an event like this:
+ pick all Sprite
+ for each Sprite
+ if Sprite instance variable Sth = 1
= do something