Had its ups and downs. I really liked the first batch of episodes when the show started. There seemed to be a lot of enthusiasm present in the series and I liked how, at times, it seemed to almost go out of its way to stand apart from the others.
I never cared for the Xindi arc. It didn't feel like a prequel to me at that point. I realize the show was in trouble and it had to be shaken up, but I didn't think that was the best direction to go in. Earth was in danger of being destroyed. Well, we knew it was going to be destroyed (since it was a prequel), but we also knew that it couldn't be destroyed anyway. Berman and Braga would never have done that -- just in an alternate reality.
Obviously, because Enterprise was produced AFTER the other series, but takes place BEFORE, realistically, you couldn't reference a yet-to-be-created story, but you'd think the Xindi incident, as big and pivotal as it was, would somehow have crept into the other shows in some sort of reference, even if it were as vague as "Earth was in danger of being destroyed in the mid 22nd century." You know what I mean?
I didn't like how they, sort of, danced around the cannon. In other words, by getting around the Ferengi encounter in the first season by only having Trip, Archer, and T'Pol see them, and not even have the Ferengi identify themselves, thus they never finding out their species. I just got the notion they were dancing around the franchise cannon.
One episode I was ready to hate, but ended up REALLY liking was the Borg episode, "Regeneration," from the second season. I remember coming here to TrekToday and reading the article that the Borg were going to show up. I thought, "How... is that even possible?" I thought it was really a cool idea to have the events in this episode, more or less, set the rest of the Borg encounter on other series in motion. It's fun to imagine that the Borg cube Q flung the Enterprise into the path of in "Q, Who?" could very well have been on course for Earth after just receiving the distress call from the Borg in the 22nd Century.
When season four started, I thought, "Now THIS is a prequel!"
Season four should have been season one. Keep "Broken Bow" as the series pilot, of course, maybe have one or two stand alone shows, but then go right into the mini-arcs that we had in season four. I often wonder how the show would have been perceived had it started like that. Mentally, I pretty much wiped out seasons one, two, and three and treated season four as the start of the series. I just felt that that's what the show should have been. To me, that's when it really felt like a true TOS prequel and not TNG prequel.