What are the advantages of a separate tethering app over the built-in tethering controls? I just rooted by AT&amp;T Galaxy S2 (SGH-i777) to troubleshoot battery usage. I also would like to tether my laptop (OS X Lion) to make use of my phone's data connection intermittently while traveling. 

I see both "USB tethering" as well as "portable WiFi hotspot" under Settings --&gt; Wireless and network --&gt; Tethering and portable hotspot. Should I use this feature or install an additional tethering application?

What [if any] are the advantages of a separate tethering app over the built-in tethering controls?
This is probably largely a preference thing, but a couple of things I can think of off the top of my head:


The built-in tethering may only be usable with an extra fee on top of a normal data plan, whereas third-party apps with work regardless. I'm not really privvy to AT&amp;T's plans these days, so I can't say for sure in your specific situation. This mostly only applies to stock ROMs, as a non-stock ROM usually also subverts any kind of tethering fee (e.g. CyanogenMod).
Many third-party tethering apps will give you a display of data in/out when running so you can keep track of your data usage. Some also display battery level and temperature.
The built-in wireless tethering provides WEP/WPA encryption and the like, but some third-party apps support additional security such as MAC address filtering and the like.
Not all devices are supported by all third-party apps, but the stock tethering should obviously work on your device if it's enabled in the settings. Third-party apps may in some cases require a custom kernel in order to function the way you would expect (in infrastructure mode) and will create an ad-hoc connection on unsupported devices/kernels (not really ideal).
The built-in tethering may have better widget integration. On CyanogenMod ROMs, for example, you can enable/disable the wireless hotspot from the power control widget, whereas you'd need a separate one for a third-party tethering app.


If you don't need the "power" tools and such then the stock tethering should function fine. I've generally used that on my EVO and I certainly have no complaints about stability or speed as compared to other apps I've tried. From that standpoint I've not noticed any real difference.