I took the plunge on Game Dev Story and played for about 30 minutes, here's the general gist and impressions:
You run a gaming company, you have to hire staff in various capacities. All staff members are rated on their ability to produce the various things a game might need (programming, writing, creativity, graphics, sound). At the beginning of the game you can only hire 4 staff members (I badly need to expand my office but I can't figure out how!)
Once you have some staff, you can either take a contract job (where you have about 10 weeks to produce certain levels to meet the contract for some quick cash) or make your own game.
Making your own game works like this:
1) You pick a platform - the PC is free but has low distribution, while any of the consoles require a licensing agreement first, which can cost a lot of capital.
2) You pick a genre and a theme - both can be discovered as your staff level up. So you might want to make a Pirate Puzzle game, or a Ninja Racing game, etc.
3) You can bend the development (better quality or speed) in exchange for more budget.
4) You then allocate "creative points" across 10 different areas. So you could make the game niche, or cute, or polished - you can't do it all, of course.
5) Development happens in stages, and at the beginning of each stage you are allowed to pick a staff member (or someone outside the company) to do a key component - the story proposal, the graphics, or the sound. As development goes on, your staff will add points to the various buckets for the game - you don't have to do much. Sometimes a staff member will approach you about going for a boost in one area - you have to spend cash and research points to do so, and it's not guaranteed.
6) When the development meter hits 100%, your staff will begin lowering the bug count (which you probably saw growing during development) - squashing bugs gets you research points, although you can ship before they're all fixed.
After the game ships, you get Famitsu-style reviews and then you get to watch the sales data until it falls off the charts. And then you can start again!
There are items to buy to boost various things, you can level up your staff with research points, you occasionally go to press conferences as new consoles are announced (Senga announced the Exodus, which made me laugh), you can take out advertising to grow your fanbase, you'll get copies of magazines with helpful articles, I even got a fan letter from some kid who failed his math test because he loved my games so much. I'm sure there's a lot more from the screens on the app store.
The game definitely feels like a port from J2ME, as there's an option to have a D-pad show up - but it controls just fine without it. (There's also Save buttons everywhere, but the game does autosave when you quit.) The game doesn't entirely explain itself but there's a manual. The localization is quite good.
$4 is high enough of a price point that people with $200+ phones are going to hem and haw over it, but I love it!