I think it would have been interesting to have Patrick Stewart play both roles instead of Tom Hardy. No reason to change the script- not only would the whole clone thing be dead on but Stewart could pull it off well.
The two Dr. Bishops in 'Fringe' show how well two versions of the same man with two different histories could interact...
One of the many lost opportunites.
Remove the stupid dune buggy
Remove B4
Remove the mind-rape stuff
Redo the dumb "Shinzon spends ages persuading them he's good, then in the next scene they find out the truth"
Bigger roles for the non-Picard non-Data crew
For a radical change, they could have done was kill off Picard early in the film, say on buggy planet, and have them encounter his evil twin at Romulus. Have Data die at the end of the film too, as Spiner was far too big for his boots at this point.
This would have allowed Riker to get the big E after all at the end, Worf as his first officer, the family could then stay together, get rid of the two most expensive characters. For bonus points, find a good way of having Picard come back at the end
However even a few minor changes in the wedding scene would have been nice
1) A brief conversation between Guinan to Worf about "Ambassadorial life didn't suit you // no, Alexander is far better at it". Remove the stupid Worf-Hungover part. If OBrien + Bashir can cope with Worf's bachelor party, Worf can cope with Rikers
2) I'm glad they cut the Wesley-back-in-starfleet line out, but a quick explanation as to why he's in a trek uniform (or just have him in civies)
The apparent ignoring of previous facts by the writers (Where's Lwaxana, why's worf in uniform, what's Wesley doing,) was fixed in the books, which is great, but should have been in the film. The character assassination of Worf continues after his zit in INS though
