rampancy: My opinion is just wait. Usually a 10.x release from Apple usually has one or two fairly noteworthy (but usually not show-stopping) bugs out of the gate, which usually gets ironed out in the 10.x.1 or 10.x.2 releases.

Also, it always inevitably takes time to figure out what apps got broken.

My advice would be to compile a list of Mission Critical apps you need to run, and then verify if the version you have will run in ML (MS says that both Office 2008 and 2011 run perfectly in ML). Hopefully you won't have to pay any stiff upgrade fees for your apps, but it is worth noting that historically, a lot of indie/shareware devs use a major 10.x software release to (usually, nominally) charge for upgrades, to try to make some money to support further development and maintenance of their apps down the road.

My second piece of advice is to head on down to Ars Technica, grab a good glass of wine or your favorite beer, and read John Siracusa's famous exhaustively in-depth OS X review to get a idea of what's going on behind the scenes in Mountain Lion.