We first heard about the iCade Mobile back when the unit was introduced at CES this year, and as mentioned last week, it's now out and available. I've been playing with one for a couple of weeks now, and I can tell you that it's an impressive device. The unit is sturdy, the buttons work great, and the whole device does a terrific job of turning your smaller iOS devices into something like a Sony PSP-style handheld console.
There are a few drawbacks, however. The biggest one is the same issue that all of the iCade devices have had, popular as they may be: Compatibility. While the list of games compatible with iCade is already long and growing, the list of games I usually play on the iPhone is even bigger, and most of my favorite games aren't ready. There are a few quality games on the compatible list (including a few giant arcade collections from famous companies like Namco and Midway), so there is definitely plenty to play with the iCade. But if there's a game you love that's not on the list, it obviously won't help you with buying the product.
If your favorite game is compatible, pairing your iOS device with the Bluetooth-enabled gamepad is a simple affair. Getting the iPhone or iPod touch inside the rubber holder in the middle is actually the hardest part of connecting the two, though it's not too bad, and once its in, it fits securely.
The other main issue with the iCade mobile is that while Ion Audio has wisely and faithfully designed the unit to match up to Sony's handheld PSP console, it has chosen to instead label the buttons as 5, 6, 7, and 8, which are presumably what they correspond to on a Bluetooth keyboard (all iCade units use the same protocol, which makes it easy for developers to program compatibility into their apps).
But even games that are compatible with the product don't tend to make use of these markings, so playing with the iCade is often an exercise in trial and error. It's not usually clear if the unit is working right away and which buttons do what. One-button games are obviously not a big problem, but more complicated games can be frustrating. Labeling the buttons with clearer symbols (and having better designed compatibility in the third-party apps) might make the experience smoother.
Once you get everything working and know which buttons you're pushing, things work great. The buttons have a nice press to them. They might be a little loud if you're a real stickler, but I like that they're tactile (which is why iPhone users want buttons in the first place). The d-pad isn't the best I've ever used, but it too is well-defined.
The triggers are less impressive. They're a little too small, and the bumper buttons can be hard to reach, especially if you have big fingers like I do. But at this point, not many games use them anyway, and I haven't seen one yet that uses all of the buttons available.
So it all comes down to developers, essentially. If there's a game that you love that's iCade compatible, I can't see any reason not to pick this device up. It's well built, and it makes games that require precision especially responsive. But odds are that your favorite games on iOS aren't yet included in the list, and if that's the case, you may find it easier to wait. Many of the best iOS games take full advantage of the phone's touchscreen, and obviously you don't need an iCade for that.
In the end, Ion is bumping up against the old chicken-and-egg problem: More developers should support iCade, but in order for them to want to do so, more consumers will need to buy iCade in the first place. Hopefully we'll see more and more games support products like this, and these ever-more-popular control units will become ever more useful. At least, until the audience gets big enough, and Apple decides to Sherlock it right away from everyone else.