The general concensus seems to be: If you're directing it yourself leave the directions in. If you're not, don't include shot descriptions.
Sometimes it is hard not to include them though. I'm not sure if it matters if you do or not.

i think it will vary from director to director. I know most directors would rather come up with the shots themselves rather then have the writer tell them what to do. Since setting up teh shots is a big part of what the directors do. But if a shot is needed to be shot a certain way then it should be fine. But if your directing it you could write anything in the script. "yo buddy, make sure this shot is like this..." ?:D?. However, if you arent dirceting one of your scripts chances are, as has happened to me, the director is going to change some of teh script anyway and your vision probably wont be the same as the directors. But once again this depends on teh director. Some enjoy having a close relationship with the writer while others want the script and the writer never shows his face or is talked to again until the end of shooting. just a random fact. In the original willy wonka teh movie was written so that it was suppose to end with them crashing through the ceiling and soaring over london. But the director didnt like that ending so he asked the writer to add to the ending a happy (and rather cheesy) closing scene. The writer didnt want ot do it but the producer told him to and they gave him more money. It's all about the bling bling...

"I believe the cinema is one of our principal forms of art. It is an incredibly powerful way to tell uplifitng stories that can move people to cry with joy and inspire them to reach for the stars."-Wes Craven