Very interesting and fun.
This game was a fresh concept which was simple to understand and to play. It took me a while to figure out some levels, although a lot of them were actually very easy, even on the hard mode there were some hard levels. Understandably, it would be somewhat harder with the timer on in the background if I had it enabled, but once you've gone through the game a few times you could just play it with the timer on and you'd know exactly where to place everything to light the nodes up.
Other than that, this game had a cool concept and I had a lot of fun with it. I haven't tried the level editor yet, but no doubt I can get quite a bit of fun making challenging levels with that too, so this game is very fun and if I had more patience I might try to make my own very, very hard levels.
Hope you get round to making a Nodes 3.