I still enjoyed it the last time I saw it so I don't think my views on the show itself have changed much.
But my views on the characters have definitely changed. When I first watched it I was very subjective so I would overly defend the characters I liked, and be overly critical of the ones I didn't
Whereas now I am more sympathetic to the characters that used to annoy me, eg with Xander I can at least see where he is coming from and why he would do certain things most of the time even if I still don't always agree with what he does
And I am more critical of characters I do like such as Buffy and Willow. I notice more now that with Buffy especially people try to defend everything she has ever done because they really like the character, But as with all the characters she has done things that are inexcusable - even though I still love the character I dont mind criticizing her when she is in the wrong. If anything it is the flaws in a character that make them more interesting
In some ways my views have changed; GENERALLY I like more of the characters than I did on my initial watches and I appreciate some of the wider themes. I love the destiny vs. choice themes that resonate through both shows. Initial view of romance: Hated the shipping/relationships stuff; specifically Buffy's relationships (I never minded any of Willow's or Xander's pairings nor ever rated any one higher than another... with one exception) but Buffy's...urgh. Bangel was boring as hell, Briley was worse because (amazingly) I found Riley less relatable than Angel; he just wasn't ever that joe-normal like. I didn't mind Spuffy until S7 when it was ultimately disappointing and tepid. Current view: Like Bangel a lot more, mostly because with Angel's show it comes across as pretty epic with both characters and their pov's front and centre for the audience to see. I appreciate every little step of the journey even if I don't (and never did) ship them. Briley improves and I appreciate some of what he does for Buffy (or perhaps how Buffy acts while she is with him), overall he's too maligned in my view. Grown to hate passionately Spuffy; one of the worst pairings in all of fiction in my opinion but my (long list of) reasons for that can be found in many other places so..
Buffy: Initially I was always on Buffy's side; team her. Wherever she was coming from I understood and accepted uncritically. One of the reasons that I so disliked Faith during my initial watch-through until S1 Angel was because she got in Buffy's face a lot, from Faith, Hope & Trick onward. And I disliked the Scoobs in DMP, Revelations and every other argument the group got into.
But now I'm a little more critical of her and can accept that she screws up quite a few times. With that came the accepting of faults leading to more affection for a character (up to a point) and Buffy is still one of the best modern superheroines in my mind (if I ignore the comics).
Angel: Only liked Angel at first when he was on his own show...actually thinking back I thought he was fine in Buffy S1..but I never really warmed to him as a hunky badass until 'City Of...' and only because the show wasn't afraid to poke fun at him at times. I found that endearing. But now I think he's a fascinating character to build a show around and S2, 4 and 5 of his show are great mostly because of him and what he goes through. He's a very fallible character (much more so than Buffy) but never stops trying.
Like I said I'm more appreciative of most of the characters now than I was initially; especially Faith, Xander, Wesley, Riley, Dawn, Fred (I found her initial 'kooky-crazy' irritating for all of S3) and Lorne (to me Lorne was a jarring, unwelcome addition to Angel's show); the one exception has always been Anya who I detested the first time and apparently always will forever after.
First of she's annoying but kind of static in her annoyingness (unlike Cordelia who softens somewhat) and her blunt unwillingness to change anything about herself. And, although I can kind-of stand her in S5, overall I thought she was harmful to Xander's development and took over some of his role/screentime. Plus she's morally bankrupt and has no real character depth as far as I can see.