TextWrangler (free text editor), Gimp and Inkscape (free graphics) or Photoshop Elements ($90), OpenOffice (free) or iWork (office like from Apple $90), or MS Office ($150) depending on what you know and who you communicate with, Firefox browser (free), Xcode for Mac or iPhone development (free), Skype (free), Tweetie, no virus scanner needed for now, and an external hard Disk so you can use TimeMachine for backups are what I have added in the first 2 months with my first intel mac.
One other thought is to use some sort of picture (instead of a fill color) for the tile backgrounds like many of the square puzzles do on the app store.
Three ideas - a picture on the splash screen that shows swipes and above and below taps and what they do with a continue button that shows up the first few times it runs, maybe with a button also for the tutorial. Two is to put a picture like this at the start of the tutorial. Third idea is to shade the row and column on the first tap with some + and - indicators overlaid (maybe) or a text box at the bottom that indicates to tap again for +_. This may need to have a way to turn it off if the user doesn't like it.
One other thought is to make the "Solve New Puzzle" more visually distinct. It took me a few taps to figure out the screen.
I looked at it. From the blurb it was not clear to me how it worked. I downloaded and used the tutorial. That made it clear. I would add something like "For you math Wonks!" It isn't the normal iPhone puzzle game. Also you use sort of non obvious gestures maybe find a way to indicate the +- ones on the main screen. I can see the average iPhone puzzle user hitting 1 star when they delete the app.
This happened to me when our company moved at the height of the 1st dot com boom and ended up burdened with space that caused us to close (rumor said about $1mill / 100 people). It certainly was months of disruption. In my neighborhood I can think of Sun, Netscape, Bay Networks and SGI that had this happen. The big move is at least an indicator to look twice.
I tried the demo at http://www.polishmywriting.com/ and it found some mistakes I missed in my writing. I am impressed with it's suggestions although it suggested many technical words as spelling errors. Check it out on your writing.
From an Apple iPhone user point of view this makes good sense as most of them will upgrade to V 3.0 pretty quick. I also assume this will help Apple regression test V3.0 with the current code base of App store applications. It might be painful for current developers but I think they can still build for V2.2.1 and then test on V3.0 also.