I bought one of the very first IMs made and still have it in my game room. About 3000 plays on the machine so far. The game is still great and I still love it. Below are a few thoughts where the rules could be improved. Hopefully Stern tweaks the rules for us who bought the original when the VE comes out.
IM rules, as they are, are great, but somewhat shallow compared to something similar, like SM. In SM every character has 3 distinct modes (sandman, venom, goblin, doc ock). In IM only the IM targets have 3 distinct modes. For the others, there is only 1 mode each (whiplash, war machine and monger). Seems like they ran out of time?
I love IM, as it is fast and furious, but where it is lacking is in depth.
As far as the scoring, I think IM is balanced and nothing I can think of tweaking there. Just basically the depth problem is what I could see being improved.
Although, I supposedly "losing" about 1000$ of value on my IM machine due to this announcement from stern to remake games, I am glad they are doing it as it gets more great pinball machines out there and hopefully the rules will be upgraded on my machine.