The recent post by SantosJ reminded me of a write up I did for the dealnews developer page. His post dealt with the good and bad of coding with PDO. For me, it was about speed, not ease of use. I will write any freaky code to save a cycle or two. In my tests (code is on the linked page), I found that PDO was slower than mysqli in every test except prepared inserts. Since the bulk of our application (and I suspect, most web apps) is read bound, that is not a big win for me. I was happy to see however that mysqli was in no way slower than the trusty old mysql extension. Good job to whomever did that extension.
MySQLi vs. PDO (my version)