I havn't come across lots of gear that is clearly an upgrade. Mind you, it would have to replace the best of what was available in TBC so everyone's mileage may vary on that one and Im sure the rewards get better as you go.. that said:
Among the initial quest rewards, it's clear that Paladins are still going to be choosing their plate on similar itemization standards as in TBC. There are LOTS of pieces with raw Spell Power on them. I don't want to say that it's exactly the same though since many of the pieces have large amounts of Strength and Stamina as well as Spell Power. Now.. Strength and Spell Damage in TBC wouldn't make much sense but the itemization works better now. So far, from the limited bit that I've seen it appears that the generalization of gear was more a move so that no one could accuse Blizzard of itemizing retarded combinations that have no value by making EVERY stat of some value. I'm certain that as we get further we'll start seeing that pieces become more generic.
I've also noticed that there are a few early quest rewards that have Spell Power, Crit Rating, and Stamina (plate) on them. By TBC mentality a strange-ish combination (for PvE gear at least) but I'm just not sure yet how it'll fair for Paladins.. Death Knights are another story.
I havn't been able to justify any other weapon either. My Tempest of Chaos looks more appetizing than anything I've seen so far. By the old mentality, a Cudgel of Consecration looks more appetizing than anything I've seen. I havn't taken the time to REALLY look into the mechanics changes (I don't plan on concerning myself with that until either they unlock 80 or the expansion goes live) so I can't say if there really is any value in early quest reward greens.
As far as how fast gear becomes obsolete. I'd say if you have decent beginner's epics (ilvl 110-115ish) the first few quest rewards will be of debatable value.. at least until we work out how the mechanics have really changed.
I'll try to find some links for some of the gear.
EDIT:
Found a nice page @ wowhead that was pretty nice for early upgrades, but with the builds changing all the time I'm not sure how long this info will stay good.
http://wotlk.wowhead.com/?quests=10.3537
Edited, Aug 5th 2008 6:57pm by Losie