This one is definitely easier than the previous two (better NPC AI, more partners to ask to do stuff for you.) So, you might want to start with this, and progress to the harder, older ones later. Of course, that might backfire, and you might really hate the other two after playing this one, since they're way harder (and have lots of block pushing puzzles, which everyone LOVES - not.)
In my experience, you should definetely get Lost in Blue 3! It is better in almost every way - there are more characters, and a much better storyline, which motivates you to keep on going when the game gets repetitive. Also, the difficulty has been lowered so that it is less of a near-death struggle to play (but its still challenging because you have a whole 'family' to look after now).
The only bad things are the blantast sexist aspects (girls cant climb as high etc) and that furniture doesn't move along with you when you move house. But apart from that, definetely get 3.