I liked the first book a lot (and for years and years it was the only one I'd read, until I found out that later there had been others written, and eventually I pulled those from the library, reread Sabriel, and then read the others). I wasn't all that bothered by Sabriel's competence and the lack of suspense that resulted from it, not directly, but I did occasionally find myself a bit irritated by the constant Narrowly Escaping A Fate Worse Than Death, But Of Course. I was also somewhat bored by the romance, but I was more in it for Mogget and the setting than anything.

As a general rule, I liked the characters in the next two books more. Sabriel was okay, but slightly boring to me as a character; I found Lirael much more interesting.

That is, that Sabriel can’t die because there has to be an Abhorsen, and she has no kids. (Presumably, it could also pass on to siblings or other close relatives, but she seems to lack those, too.) One day, I want one of these people to be stuck living forever because they’re sterile.

This does get played with a bit (although not in the 'stuck living forever because they're sterile' sense) in the next two books, I think.