I'm not going to say anything until I see the final film, but it's not like some other director got the script. It's still Spielberg. You can complain about how bad Spielburg killed ET or how bad Lucas killed Star Wars, but still:
Spielberg's last film - Munich (pretty damn good, nominated for Best Picture)
Lucas's last film - Episode III (by far the best of the prequels and better than ROTJ)
That being said, the movie could still suck, but with Spielberg directing, the movie's in good hands, and I'm sure it won't suck too badly.
Again, even with Spielberg, I really can't be too excited about a script that has Indy vs. Aliens.