I play an archivist in an eberron game and she's incredibly versatile and alot of fun. Since the party doesn't have a cleric or a wizard, she has to fulfill both roles sometimes. However, I think the success of the class is highly dependant on your GM and setting - because getting all the spells to be versatile is very expensive, and it takes some cooperation from your GM if you want things like domain spells and divine bard spells (chortle). Luckily for me, in this particular campaign we have crazy stupid amounts of money, my character has the equivalent of 1/2 a boccob's blessed book (saves on scribing spells), and the GM let me take "collegiate archivist" (there's a collegiate wizard) feat, which gives me 4 cleric spells (instead of 2) per level.
With artificers around, it's relatively easy to find a 4th lvl Paladin or Ranger spell, or a 5th level Divine Bard spell, or any druid spells I want, but i imagine in a "normal" campaign, your chances of finding paladin or ranger only scrolls are alot slimmer, and finding paladins or rangers that can cast the spells to help you make a scroll even harder..
My archivist is primarily the party's healer, so I took a level of a 3rd party suppliment prestige class called "Healer" that gave me the healing domain as a 1st level ability, and then I went into combat medic - so now I can spontaneously cast the Heal spell.

Now I'm back to Archivist - the dark knowledge powers are fairly useful, especially the saves vs. monster abilities, that's saved us once or twice.
Someday I'd like to play an archivist in a more normal campaign, but I think I'd be frustrated by the difficulty of finding spells and the expense, and possibly the lack of divine bards and shugenjas to get spells from..

OTOH, it would be a great deal of fun to actually get to RP the class as described in the book..
/ali