I feel like that's the Trek films in a nutshell - from a critic's standpoint, they're not necessarily all great, but they almost feel like long Star Trek episodes that you enjoy anyway.

Here's my thoughts on each film:

• Generations: Honestly, I think pretty good with a solid overall plot. I loved Data's arc - I feel like they did a great job not taking the comic relief too far. The fight scene was delightfully campy, and the "Time is a predator" stuff is so memorable to me.
• First Contact: I think it was a fun film. It's almost the Wrath of Khan of the TNG films - a lot more action, with some Trek - which is probably why it's considered the best. Personally, I prefer Generations, but this is still a good watch.
• Insurrection: There were a lot of fun moments, but the overall plot wasn't that great - Picard's new love interest that we never hear about again, the weird theme about "being in the moment" that I feel didn't integrate into the plot all that well, etc.
• Nemesis: I think Nemesis had a lot of great things that didn't quite land at the end. I think Shinzon did a great acting job, but could have been written better. They made him more irrational than I think he should have been, and the whole plot with "blowing up the earth" and "conquering the galaxy" felt way out of line for someone who is the product of and survived imperialism. As for B4, I feel they didn't address the ethical concerns of throwing Data's mind in him. At the end, blowing up Data didn't help, but if the rest of the movie had been written better, I might have been fine with this choice, Chances are, whether through B4 or a Search for Spock-esque plot, we would have gotten another film where we got Data back.