Puzzle Quest just keeps layering on the goodness

So, after meandering through a bit more Assassin's Creed I found myself strangely not caring that I had no idea whether it would save my progress correctly given the wacky and cumbersome route you must take in order to exit the game. Not a good sign.

I turned my attention back to Puzzle Quest for the rest of the evening and was not disappointed. The core mechanic of the game, remember, is piece matching (get 3 or more in a row). There are even "minigames" that are, well, basically the same game but with slightly different rules and victory conditions. And even though the core mechanic is the same, I haven't become bored with the game yet.

In fact, the more I play the more I like the game.

I think there are a couple of reasons why it gets better over time:

• The core mechanic is already proven and fun. Who doesn't like Bejeweled?
• The game is easy to fit into a busy schedule. You can spend anywhere from 5 minutes to 5 hours and quit at any time without losing progress. You can leave for days and come back and it's easy to pick up. Even though you might forget some of the optimizations you've made, you'll quickly rediscover them through gameplay and as you level up and progress.
• Just when you think that you might have had enough, another gameplay element will be layered on. For instance, I felt like I was having to penny pinch too much and was worried that this might make the game progress too slowly. Then I unlocked a siege tower and now I can besiege cities which is both cool and a way to beef up my income via the outer map game (instead of just racking gold during battles).
• Even though I know I'm just playing a spreadsheet (and, in fact, when you level up you see all the percentages and decimal places that reinforce the spreadsheetness of the game) the systems are tied to the game fiction in cool ways (e.g., as followers, mounts, weapons, etc).

One interesting aside that might be worth exploring later: Many people criticize Assassin's Creed for the repetitiveness of the gameplay (find town, climb tower, pick pockets, assassinate boss, run away, lather, rinse, repeat). Why does Puzzle Quest get a pass in this regard?