Back in 2001, people hated the show, because it wasn't Birth of the Federation. Why did it need to be that? I was fine with it simply being a pre-Federation Enterprise having weekly adventures a decade before the Federation. I do agree that there were times where it felt like the show forgot it was a prequel. A lot of S2 episodes felt like they could have been Voyager episodes.
S1: Strong season! Loved it start to finish.
S2: Got stale, felt episodes could'a worked for VOY or ENT or even TNG.
S3: The Xindi saga, my favorite season overall of the series.
S4: I honestly didn't mind the shift to prequel-mania given they knew there was a 99.99% chance of cancellation.
The only fan service I didn't like was Klingon foreheads, because it was just stupid. I liked the two-parter, Klingon augments, deadly virus that needed curing, everything was great - just drop the forehead thing. I did like the series finale - for what it was trying to be. Great ideas, but last-minute cancellation... people are too hard on B&B. They had a season finale and had 5 minutes to rework it into a series finale. They tried.
I kind of like how the show shifts gears, changing premise and tone twice over. S1-2 exploration, S3 the Xindi saga, S4 the Federation begins. Then we get a "6 years later" flashforward because cancelled.
S1: Strong season! Loved it start to finish.
S2: Got stale, felt episodes could'a worked for VOY or ENT or even TNG.
S3: The Xindi saga, my favorite season overall of the series.
S4: I honestly didn't mind the shift to prequel-mania given they knew there was a 99.99% chance of cancellation.

I kind of like how the show shifts gears, changing premise and tone twice over. S1-2 exploration, S3 the Xindi saga, S4 the Federation begins. Then we get a "6 years later" flashforward because cancelled.