When a 3rd party app comes out for a specific service after the company offers their own, there's got to be something specific it targets or else why would anyone use it? The GarageBuy app for the iPhone is an eBay based app that offers something geared a bit more towards the people looking to snag a last minute deal or fight for a specific item of interest.
To take full advantage of this app, you really have to give it permission to access your eBay account. Enter your username into the prompt, then follow it as it redirects you over to Safari to fill out some more information and get that authorization. Now you'll be able to mark items to be watched and even place bids on them directly from the app.
But what about sniper specific features? Well, any item you search for that has a bid on it will display it's price in red. You'll also be able to see the cost of the item and the time remaining all from the main screen. That means you can view all the items that are almost ready to end and bid on them accordingly in real time.
Just like with the official eBay app, there is some delay to the bidding unless you're on WiFi. But even then you can't expect perfection as it's not the source directly. The app doesn't make it easy to view information on the item either, it just sort of plops the full web page out on your screen without leaving the app for Safari. If you're an eBay sniper, pick this app up. If you're not, you'll have to be the judge as to which app is better for you.