Unlike weapons of legacy, not all of them have power progression. Some of the weapon artifact do (like Eldros' Panoply) do in fact go up in power (much like set items), but only one I'm aware of that levels with you is the Bastard of Exalted Deeds.
There are no feat requirements (usually) but some have unusual activation in terms of you might need to spill blood to get them going.
It's very much like AD&D/2nd edition D&D. Book of Artifacts. There are some that can screw with your character, but those are generally the evil ones. Bastard of Exalted Deeds is kind of the exception (along with Eldros' Panoply), but hey that's why I like it!

Not all change your alignment but some can. Some can also do massive harm to you, your friends, your friends' friends, and so on. (What, you thought blowing the Horn of the Apocalypse would make you cool some how?!)
A good number are indeed campaign starters/breakers. But there are some (like the King's Pepper Grinder) that can be considered "strange magic items" that might be useful down the road. Most though, are artifacts. That means they are either starters of campaigns or enders. Some can be both. Most though are pretty fun to read and consider using. Trust me, even if you hate EVERY SINGLE one, Olaf, the appendix in the back for creating your own artifacts is worth at least 25% of the book's cost. That and the complied mechanics aren't too bad either.
Plus, if you want a REAL beer and pretzels game, go with my thought, the Siege Hound of Dhula'zar versus the Juggernaut of Shaddar Khan. Your players (if they are fans of old Godzilla/kaiju monsters) will love you for it.
Ari,
Just curious have you and C.A tried my suggestion?