One thing you need to point out is that Confessions was the first auto-biography. He was recording his own journey of faith, of course he's going to be in error, because it isn't until much later in the book that he actually accepts Jesus as his Lord.
It is important to point out that Augustine is considered the father of Western theology. The big split between the Eastern and Western church had to do partly (not entirely) with the fact that most clergy in the West thought of Augustine very highly and the clergy in the East barely knew who he was.
Even the reformers such as Luther and Calvin were extremely fond of Augustine's theology and for the most part adopted it wholesale as a foundation for their own beliefs and teachings.
http://en.wikipedia.org/wiki/Confessions_(St._Augustine)
It is important to note that his thoughts on the trinity are the building blocks for most modern theology -even if you don't like it.