The episode had potential, but in a nutshell, I think the reaction was so strong because the episode followed seconds after the previous (UPN aired them back to back), which put Trip and T'Pol back on course with their relationship, and was an exciting and emotionally strong episode. It did, in effect, tie up some loose ends lying about the series. Then the actual finale starts off by saying Trip and T'Pol ended their relationship within months of the previous episode. So all of that build up and character development was for naught. Trip's death? I was okay with the character dying, but it was rushed and there was no reaction from most of the other characters. The only thing his death did was keep him from appearing at the end of the episode. I'm happy he went out saving the ship, but it was saving it from a group of thugs with no series history who looked like rock stars. Plus the poor guy doesn't even get a death scene. Not even a bad one.
Riker and Troi: I understand, people age and years have passed and TNG uniforms are unforgiving. The moment I saw Riker and Troi, all I could focus on was how much older - and larger - they were. It was painfully obvious 11 years had passed since The Pegasus was filmed. There was no real suspense or interest to Riker's story since we knew Riker was going to talk to Picard - we saw the episode already. What would have made this more visually consistent and even more interesting would have been to place the holodeck on the Titan and have "present day" Riker and Troi deal with the issue. And, seriously, doesn't Marina Sirtis even try to sound like Deanna Troi anymore? She was, frankly, terrible, not to mention smug.
Honestly, I don't mind an episode treating Enterprise as history and being used to help solve a problem via the holodeck. It was just so poorly realized. I didn't mind missing Archer's speech if only because we already got a rousing alien-unity speech at the end of Terra Prime, and it was a great speech. I don't think anything would have topped Soval being the first to stand and applaud. Hell of a character arc.
I consider it a fair episode and there are a number of well done and interesting scenes. Seeing the Galaxy Class Enterprise again was great, and if this were done in the second season, it might have been something of a standout. However, as a finale, it fails to do justice to a series which had gotten its act together gave us two consistently good years. It deserved a full run, and I still hate that they were robbed. But them's the breaks.
Had they used Demons/Terra Prime as a two hour and put the ending montage on THAT show, it would have been an amazing finale. These Are The Voyages is a fair episode which falls short of potential. But as a series finale, it's horrible. The bitter taste it leaves is augmented by the fact that much of the cast hated it before we did. Although, I loved when Archer hugged T'Pol. That was a nice "thank you" for everything.