I thought about Nemesis when I saw the name come up during Skyfall but I shrugged it off and didn't give it a second thought until I saw this thread.
Nemesis isn't a bad movie, its just not a good movie, but it does have the right elements that it could have been a great movie…the problems are definitely with the story choices and especially with the background of the antagonists and his plan.
While I don't see a problem with the Remans cobbling together a ship of their own and even developing a super secret weapon I do find the overall concept of the Scimitar just a little OTT and fan boy is. Massive ship which not only has the mentioned killer radiation feature but can also fire while cloaked and remain shielded but also dwarf anything Starfleet or the Romulans can throw at it (without hitting it with an entire fleet).
Picard should not have been shown as a Cadet with a bald head, having Tom Hardy with hair would not have been a "who's this guy" in the photo.
As for Shinzon himself it could have been more believable if they had mentioned that he had been engineered to grow quickly with outside influence, when the plan was scrapped he aged at a more normal human rate but not without some problems, prematurely loosing his hair being an early outward sign.
Then we get to B4, Shinzon places a Soong type android on a planet near the Romulan border to lure the Enterprise in, bit of a gamble seeming any ship could have detected the reading and investigated. It would have been better for the mysterious new Praetor to have specifically requested the Enterprise to attend talks of peace considering its legacy and the exploits of its current crew. B4 could then have been noticed on the way there by planting the spy, of course Picard would have been able to divert for only a short time on such a crucial meeting.
The dumb dune buggy chasing to track down an android who's origin is never explained just to put the Enterprise close to the neutral zone is a bit of a stretch, even if it does allow Data to sneak aboard the Scimitar to save Picard as well as download his memories to complete the comparisons to TWOK just wasn't needed and after it becomes a fairly decent scifi action movie with a passable plot.