I avoided watching this for 20 (!) years, because the reviews were ambivalent. But it's really fun. It's not awesome, like the Kirk/Spock series, but it's also (thus far) not excessively moralizing like TNG.
This is the only Star Trek (for me) that captures the wonder of the original series. The writing isn't great, but that was never a thing with Star Trek. They're also a bit kinetic, say, with discovering new Warp-Civilizations.
I also really appreciate that the crew is basically white, except for one black guy that's not blackity-black.
Even the chicks are fine. The writing for the Asian chick is a bit insipid, but it accurately reflects the chick version of the 'hero's journey'.
Unfortunately, they've introduced Time Travel, so I guess a few of the episodes are going to be tedious.
I've watched everything Star Trek and Enterprise was also the last thing I watched. I just finished it for the first time literally a month ago. When I was younger I avoided it because I thought the starting theme music was too gay.
Enterprise got a lot of decent reviews but riding off the coattails of DS9 and TNG with a complete 180 in theme was already going to be difficult. DS9/TNG has just nailed a winning formula and the next Star Trek abandoned it basically so a lot of Trek fans were upset. People at the time wanted something along the lines of TNG/DS9 but a little different, not something as different as Enterprise.
Overall, I enjoyed Enterprise. It's worth a watch. I didn't think Enterprise did anything exceptionally well and nothing was too memorable about it but it was still enjoyable. If you're enjoying it only 18 Episodes in then you'll definitely start to enjoy it more. The last 2 seasons were probably the best and I thought the first half of season 1 overutilized some themes as they were still trying to find a groove.
I have heard that people literally hate the theme song, and by extension the entire series. It seems strange to judge an entire show on something so trivial, but it's a complaint I see often when the show is brought up. That and how much people hated the final episode- which seems to be something so many shows get wrong.
I think it started out slowly and didn't find its groove till the end, but if you watch the first couple seasons of TNG or DS9, you'll see the same thing. The first season of TNG is a excruciating, as you can almost feel them stumbling while trying to figure out what each character's personality should be.
I think the show suffered from a form of fan service: "we've got to show the Borg", Let's find a way to work in Data's creator", etc., but at the same time, those were some interesting and fun episodes.
Given the prequel setting and how they worked in so many references to the previous shows, it almost feels like some sort of retrospective send off to Star Trek, which now seems appropriate as pretty much everything in the franchise since then has been trash.
The first season for really bad for way too many shoutouts to future Star Trek stuff. They toned it down later on though and made it seem less forced which was better.
All Treks except DS9 started very shaky imo as you pointed out but Enterprise was essentially riding off the coattails of DS9 so people at the time had less patience for bad starts. Compared to TOS, the TNG+DS9 era really advanced the technology in the Trek universe and the high-tech was fun. Enterprise went backwards where there was less tech which was not exciting for Science Fiction viewers. Then combined with the opening theme which in itself seemed the very opposite of progressive (it sounds like some sort of Christian Rock song... Faith to believe, lmao) it just seemed to be all the wrong messaging.
I listened to the first five notes of the theme song... and have never listened to it again.