For those people who are adamant about building a PC around an AMD CPU, I generally recommend the Phenom II over Bulldozer. The Phenom II generally does a little better in some applications. I think Bulldozer outperforms the Phenom II when you are compressing files (WinRar) but who buys a PC solely for using WinRAR? I think Bulldozer also does well with Adobe. But Phenom II performs a little better in most games.
I also recommend that people make up their minds fast when it comes to Phenom II or Bulldozer because it is rumored that AMD has stopped producing Phenom II and Athlon II CPUs. The large number of reported shortages of those CPUs tends to give that rumor some validity.
it all matters on price and performance in the apps you are using.
Bulldozer is a fail if it has 8 cores or 2 or 100.
currently it is 10% behind phenom and 40% behind sandy bridge in terms of single threaded performance, thats just how it is and why it falls behind in so many benches.
Its ok in threaded benches that can take advantage of the new hardware but really nothing else. The launch was forced on a unready product, it could have been ok but everything about it looked rushed and unready.