Originally I had given this a poor review for the same reasons others stated; the game play was frustrating on iPhone.
Despite this, I persisted and at some point realized that when you have the correct placement for an item, IT LIGHTS UP! This discovery instantly made the game play easier on both iPad and iPhone. The "lighting up" is very subtle and difficult to notice on iPhone. I also discovered that placing the items slightly above where you want them to go is the best placement. This changed the game for me and Ive since made good progress.
Still annoyed by the menu access at top and the need to constantly hit the star to access it. Would be a definite improvement if you could also "minimize" the menu when you choose to as opposed to it auto hiding after two seconds.
Anyhow, cool game.
HurricaneArran about Machinarium, v2.0.1