I have a few apps on my iPhone that are large. Black's Law Dictionary is about 60 MB, the U.S. Code is about 200 MB, and I have a few apps that are around 300 MB. I see that Riven, the sequel to Myst, is now on the App Store and it weighs in at 1.01 GB. Gulp! I believe that Riven is the largest app ever released for the iPhone or iPad. [UPDATE: As Philippe Radley points out in a comment, some GPS apps with built-in maps are even bigger; for example, Navigon MobileNavigator North America is 1.52 GB.] As the developer notes, you actually need to have at least 2 GB free to install this app, and you are NOT going to want to download this one over Wi-Fi:
Riven for iOS is a VERY, VERY large application. We’ve managed to optimized Riven from its original DVD size to a little over a gigabyte. Even at that size it’s one of the largest iOS app we know of - so PLEASE BE PATIENT - download times and syncing times can be longer! It's possible on slower iOS devices for the downloading/syncing to pause FOR 10 OR 15 MINUTES.
Because of the large size it's HIGHLY RECOMMENDED that you download Riven on your computer using iTunes, and then sync with your iOS device. Downloading directly to your iPhone, iPad, or iPod touch is theoretically possible via a wireless connection, but... uh... well... you really don’t want to.
It is pretty rare for me to play an immersive game on my computer, but after all of the attention that Myst received for being a landmark computer game with incredible graphics back in the mid-1990s, I bought Riven when it was released in the late 1990s. I remember that it took me a very long time to finish the game, but I enjoyed playing it for hours and hours becasue of the incredible graphics, far better than anything I had seen at the time on a computer. Presumably, the Riven app is so large because the developers brought all of those great graphics to the iPhone and iPad screen.
I don't think that I'll buy Riven for iOS simply because I've played it before (albeit over a decade ago), but I do appreciate it when any developer brings incredible graphics to the iPhone. I recently purchased an amazing iPhone/iPad game called Infinity Blade. At 318.3 MB, it is currently the largest app on my iPhone and iPad (although pretty small compared to Riven). You control a knight and fight the bad guys in a castle. This is not normally a game that I would buy, but I had to check it out because I heard that it has some of the best graphics ever seen on an iPhone or iPad. Here are screenshots from my iPhone (top) and iPad (bottom) (click to enlarge), but frankly these still images don't do the game justice. The graphics are most impressive when you look around and see the fluid animation.
The graphics are stunning, and even for a non-gamer like me, the game play is not bad either — although I have to admit that sometimes I am a little slow using my sword because I find myself paying too much attention to what a great job the developers did creating the graphics. I suppose that an appreciation for beautiful computer graphics is one of the same reasons that I love Pixar movies so much.
You can get a sneak peak into the Infinity Blade world by downloading the free Epic Citadel app from the developer of Infinity Blade. There are no bad guys to fight, you just walk around and look at the beautiful castle. My five year old son loves using Epic Citadel just to walk around and pretend that he is a knight. I love this app too. In some ways, if you are just interested in great graphics, Epic Citadel is better than Infinity Blade because you have full control over your movement and where you can look. In Infinity Blade, your movement is far more restricted.
Even if you are not a game player, consider checking out one of these apps — especially Epic Citadel — just to appreciate how nice graphics can look on the iPhone (especially the iPhone 4) and the iPad.
Click here for Riven: The Sequal to Myst for iPhone ($5.99): 
Click here for Infinity Blade for iPhone and iPad ($5.99):
Click here for Epic Citadel for iPhone and iPad (free):
