I never played P4 before and for most of my playtime so far (9 hours?) Chie is my favorite girl in the game. Mostly, I just like the idea of a kick-butt, athletic girl with an over-the-top personality. She's crazy and fun and it's refreshing in a female anime-esqe character. Yukiko is obviously the perfect waifu but, whatever. Chie actually makes me laugh at times.
Now, I have to admit, when I showed the game to my friend and he heard Chie's voice (she was freaking out about Yukiko at the time) he was like "Whoa?! That girl needs to calm down!" It was then I realized she was a bit too over-excited in her vocal delivery. I hadn't noticed until he said it, to be honest.
Then as I was reading this thread I got curious and listened to her original voice. Yeah, this new Chie has definitely more of a "grating" quality at times compared to the original which was more in line with the rest of the voices (especially Yosuke). Then again, I do still like her voice a lot for those times when she gets excited because it's just kind of fun.
TL;DR: I like her voice in that it fits her character. However, it can get a little grating sometimes compared to the smooth, perfect delivery of the other characters like Yosuke and Dojima.