The good parts were Spiner playing Data seriously, Crusher's scenes and the ship battle in the end; the crew's reactions to Data's death were OK. The rest, especially the other action scenes, seemed too going-through-the-motions.
1. Disrespect to the fans - why did no one question if B4 was Lore?
I don't think that sort of continuity is so important that not referencing it is disrespectful (and a reference to Lore could have been confusing to new/casual viewers) but Spiner's acting as Lore does make both B4 and Shinzon even more underwhelming.