Very interesting game mechanics and very fun to play.
There is also quite a lot of levels and game is quite long depending on how you play.
In most of levels, if you get noticed it is a good idea to just rush the rest of the level while the eye recovers for next thunderstrike, it's faster and simpler then trying to do everything perfectly stealthy.
Once the spikes come into play this strategy isn't really applicable so well and everything becomes much harder.
The gradual storytelling trough monologues at start of each level are a good thing to keep the player motivated.
The ending animation was rather short and didn't explain much of what couldn't be deduced from the monologues within levels. After the hard last levels I would hope for a more interesting ending revealing more details about what, why and how it happened.
Also - while the gamescreen is rather large, it would have been nice if this worked on fullscreen.