Get tetherme instead, it enables the native hotspot from the phone and not a 3rd party app like MyWi.
Not all iPhones have a "native hotspot" to enable, so TetherMe may be seen as useless by some.
Here, I posted this to reddit to explain some of the differences:
TetherMe;
Positives:
* Unlocks native tethering.
* Has APN editing (which may help if you're using an unsupported network).
Negatives:
* If your device doesn't have WiFi tethering, TetherMe won't give it to you.
* Native tethering has the annoying blue bar, unless you install other addons to change it.
* No extra controls compared to native tethering.
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MyWi;
Positives:
* Able to reduce the WiFi transmit power, saving battery life.
* Able to select tethering bar or status bar icon without installing additional tweaks.
* Enables WiFi hotspot on devices that do not support WiFi hotspot natively (original iPhone, iPhone 3G, iPhone 3GS).
* Supports OnDemand auto-connection (may not be as robust as it was in iOS 4).
* Able to use WPA2 security on devices that support it (iPhone 4 and newer).
* Able to individually toggle USB, Bluetooth, or WiFi tethering.
* Able to do "WiFi sharing" (in situations where you have WiFi access, but only one device can connect to it, your iOS device can share that connection).
* Detailed status screen showing connected clients, Sent & Received data, and current power draw (in mA).
* Ability to change WiFi channel used, AP mode (Infrastructure or Ad-hoc), and auto-shutoff time.
Negatives:
* Cost..?
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MyWi does more than just "enables tethering". It's a bit different than TetherMe. They both have their uses.
Oh yeah, I'm posting this while tethered to MyWi under iOS 6.1. WPA2 WiFi hotspot works great. I happily paid the $5 to upgrade.