[eluser]PhilTem[/eluser]
1) CI's AR class escapes the queries automatically with proper DB syntax
2) It's universal since it's an "abstract" layer for communicating with your database. AR allows you to have no knowledge of what DB system is running (postgresql, mysql, mssql, ...) you only write the queries the way you want them
3) (This may not be an official advantage, but

I personally enjoy reading AR class calls and it makes reading the queries easier since you don't have to run through a line of code looking for keywords like "SELECT", "FROM" in order to get the meaning of the query. Plus altering a query is easier and you most likely don't produce syntax errors when adding a "JOIN LEFT" via "db->join('table', 'left');"