a guy on pinside posted his thoughts on playing the game at the factory today, so below are snipets to what he thougth, though maybe a little out of context with the other peoples questions but gives you a good idea for now:

- Great shooting pin. I think everyone will be impressed with the toys in the PRO model. Not such a huge deal between versions. Love the inline drops. There's also a cool shot behind the fuel stand ups I didn't notice before. Music is great. Voice call outs are cool. I really think they'll end up selling lots of pros on this one. Fast/in your face play.

- motorized grave marker is cool but wouldnt really effect gameplay at all. At least not that I'm aware of.
Snake is on the pro but the LE/Premium will do cooler things with the snake.
Fuel bar is no big difference really from what I understand.
The hammer is a big feature on the LE that isnt on the pro at all.
Again, software is early, according to Lyman, but was fun.
My main point was if you cant afford a premium the pro is a blast and really feels full-featured vs feeling like a stripped down model.

- Pretty cool and stackable. I had at least two multiballs going at once. Maybe three (not sure about that though.) You choose music before ball launch as I recall. I stacked multiballs and had a bast.

- fulls songs I believe. I was having too much fun to be super analytical about it. =)

- The premium road case graphics are actually really cool. The translite was ok. I would much prefer the second premium dirty donny translate.

and for those that go to pinside, you can find the full thread here
http://pinside.com/pinball/forum/topic/played-metallica-pro-today