Rovio have had less than £5 of my money, and for that I have received hundreds of Angry Birds levels. Whether in the main game, Rio or Seasons, it's fantastic over-delivery and should be applauded.
However, Angry Birds Seasons irks me. It has a tendency to lock level packs to dates. You only get a level per day. Worse, it insists on validating the date against its server on a per-level basis. So you can't play it on the Tube, on a flight or in a foreign country.
It's an example of a game testing the tolerance of players for no good reason. All games have some aspect of tolerance about them (usually the point at which they ask for money) but it's always good to minimise them where possible.
It makes the player think ill of the developer when tolerance-increasing shenanigans are deployed because the player feels that he is being toyed with. Sure, you might see some temporary rises in retention rates and server traffic.
But at what cost?
(I'm on vacation for two weeks from today.)