I never had a problem with Enterprise, but after watching TNG, DS9, and Voyager (1987-2001.) I just couldn't stay interested. I catch it in reruns and there are some good episodes. I love the mirror universe one.
The problem with Enterprise is that it shouldn't have been Star Trek. They had this grand idea for making a series on the birth of the Federation, and then completely lost their bottle by just tossing in things we'd never seen before, despite the fact it didn't make any damn sense at all because it would all subsequently completely disappear in the later history we've already seen.
If they'd bothered to hold themselves to Star Trek, fine, but right from the start they'd already given up, tossed in sets and props that made their future look anachronistic before its even happened, stole the Akira design because its well recieved and pretty with a rubbish retcon that the Akira is inspired by the NX class, and started running into never before seen 'aliens of the week' despite this being what would become the core of the sodding Federation, and thus should always seem familiar to the viewers. There was just no effort to make it a Star Trek series.
Whenever Enterprise was good, it was just good sci-fi. At least when Voyager was being a complete pile of garbage, it was still oozing Trek from every pore while doing it.
I had 2 issues with ENT. One, I have never really cared for Scott Bakula.
Second, I appreciate a hot Vulcan female just as much as the next guy, but they REALLY played that card too much, IMO. When I saw the scene where Trip is lathering some kind of lotion all over T'pols half-naked body, I new Enterprise had "jumped the shark". I fully expected the back-ground music to change to "Chica-Bow, Chica-Bow Wow". Star Pron.