Premium is much better than the pro in my opinion. It's not even close on this table. I'd put it akin to AC/DC pro vs. AC/DC Premium/LE.
The magna-slings were introduced on the perfect game and make GB premium/le play different on the bottom-side than other recent games (in a good way, imo). Slimer is improved over the pro as it's not a gimme shot anymore since he's moving back and forth, often into an unhittable position. The ecto goggles are well-done and again, introduced on the perfect machine (ghosts appearing on the display). The subway ramp with below-playfield physical ball lock is just awesome. This feature alone would push me to the premium. The right ramp works fine....it just needs tweaked a bit (as do a few switches and lower ball guides). Once dialed in, this game is a blast. Best game to be released in a number of years in my opinion, by any manufacturer.
My playfield has no issues with ghosting or cracking clear. I realize not everyone was as lucky. Hopefully those of you with playfield issues get some kind of remedy from Stern. I'm still on the 1.05 code as I'm not sure I like the changes they made to make it easier to progress through the modes.