That's fine if you only need _trackPageview. The Google solution provides more capabilities though. Also, be careful of using 3rd party solution. They don't

That's fine if you only need _trackPageview. The Google solution provides more capabilities though. Also, be careful of using 3rd party solution. They don't always work correctly. The jQuery plugin for GA used to cache-bust every request to ga.js, which definitely slows down your page.