Have been playing the game for about 3 days now, and I am thrilled with it. Great game, great concept. It did take me a while to get into the game, somewhat of a slow start–for me anyways. The game itself is similar to Fallout except, as one game review puts it, "in reverse".
I have been playing this on a MacBook Pro, 2.4 GHz Intel Core 2 Duo, 4 GB memory. And, it works great. So, it does not NECESSARILY "require a powerful mac". I have noticed some lag, but I had music running. Oh, and I have been running the game at full resolution and colour and all that stuff.
Graphics: AMAZING, really enjoy the cartoonish look along with the realistic back drops.
Speed: Runs quick, some lag, depends on your computer and what else you have running.
Story: I like the story, interesting concept, very fun to play-along.
Saving: Does it in the background, works well, no issues.
Buttons: Can be adjusted to your preferences.
Mouse: Can be played with trackpad, somewhat difficult.
Sound: Sound quality is wonderful and Right & Left enabled (meaning noises will be heard in the L/R ear depending on where the sounds come from).
Problems: Nothing yet, a bit of lag, but that is to be expected. However, in the game itself: I notice the gun shots miss 30% of the time even when the crosshair is directly lying on the target. So I found that a little strange, perhaps it is a Life-Like thing they were trying for.
Final Decision: Decided on 4 stars instead of 5, only because the game started a little slow and I had a few higher expectations for the game considering the price ($49.99) which is a little high for an App such as this.