So you're saying it should be $1, or is that still a bit much? If you mean free then why not say it's not worth any money?
Wondering about Geometry Wars myself, I can comments on Pacman CE though. If you know the game then this one plays the same but with a bunch of extra modes tacked on. The Missions are basically a shitload of boring tutorial levels. The main mode is the same as the XBLA one, albeit with different maps*, and the other mode is the same but with faster scared ghosts (so they're harder to catch) for the first 10 maps, then the dark maze for the last 5.
*The main XBLA map is the last one in the DLC. If that isn't important to you then the first included one plays pretty well too. It's like a simpler modified version of the XBLA map, it flows well and has good variety to it.
The standard game has something like 5 main maps and 20 missions while the DLC adds 10 more maps and like 100 missions? The only thing I play is the XBLA map or the first one really.
Control wise there's swipe, dpad, and funky screen button mode. I use the latter on my iPhone (takes a while to get used to) and swipe on my iPad cause the blown up controls are too big to play with well. It looks nice on the iPad at least, it's one of those games that scales up pretty well.