I have been a near life long Star Trek fan. I was an activist fan and started going to the conventions in the 70s. Watched the spinoffs series The Next Generation, Deep Space Nine, Voyager, and as much of Enterprise as I could stomach (1 1/2 seasons to be exact). Please, believe me when I tell you Star Trek: Nemesis is terrible and should be avoided as it is an uninspired, unoriginal and cynical piece of filmmaking.
Probably this film's biggest sin is it's unabashed attempt to clone Star Trek II: The Wrath of Kahn. Unfortunately it doesn't have the organic magic of chemistry, time and context. It simply doesn't have the real world history that Wrath of Kahn had, and so the makers of Nemesis tried to fake the recipe with artificial ingredients. The end result was something that looked and felt forced and totally, painfully contrived.
It has been said repeatedly that Director Stuart Baird was unfamiliar with Star Trek and had never seen an episode of The Next Generation, however, I'm sure the studio made him study Star Trek II: TWoK. I'm also sure, based on an interview with screenwriter John Logan I read at the time, the studio gave him a laundry list of what they wanted and didn't want that steered him in only direction - The Wrath of Kahn.
The second biggest problem, I believe, that sunk this ship was the overindulging and excessive input of Patrick Stewart and Brent Spiner. Just because they play their roles superbly does not mean they understand the appeal and phenomenon of Star Trek because they continually demonstrate that they don't. Don't forget this movie was preceded by the awful "Star Trek: Insurrection." In fact, out of the four films centered on The Next Generation cast only "Star Trek: First Contact" was good (fortunately it was very, VERY good!).
It is a shame that this installment turned out as poorly as it did for it was loaded with talent. John Logan writing the screenplay. The casting of Tom Hardy and Ron Pearlman. Not to mention the regular cast of TNG. I mean Star Trek isn't perfect, they have done a consistently excellent job when hiring leads for their TV series (as with tribbles, however, you just don't want to over feed them lest their egocentric demands for input multiplies the problems in creating an acceptable script).