In general, you run into the same problems as you do with any Divination specialist... Divination is not a powerful school of magic. It doesn't let you mow down rows of enemies. It doesn't keep you alive when a horde of Orcs comes charging at you with pointy things. It doesn't let you escape in a desperate situation. There ARE uses for Divination... it's just that they're fewer and further between then uses for, say, Evocation. Or Abjuration. Or any other school, for that matter. There IS a reason why you only have to sacrifice one other school to specialiaze in Divination, after all...
That being said, Loremasters DO get more skills then a Wizard, and they get a handful of nifty minor bonuses, as well as (at higher levels) free identification of magic items... and, as is rampant throughout the core spellcasting classes, "+1 to caster level" is just as good as a level in the class itself... better, really, with the addition of a PrC level, making the acquisition of a PrC... ANY PrC... a no-brainer.
Unfortunately, when considering PrC power, there are plenty of PrCs that are far more useful in a standard scenario... if you're willing to put out such high requirements for a PrC, why not be a Fatespinner, or a Mage of the Arcane Order, or even a Divine Oracle?
Alternately, if you really want to identify magic items for free and have lots of nifty knowledge abilities, try the
Cloisered Cleric variant in the D20 SRD... you get more skills, the same Lore ability, free Identify at first level (via the fact that Identify as a divine spell doesn't require a material component), and three domains. Granted, this is a rather different character concept, as you sacrifice Arcane casting for Divine... but in terms of pure divination efficiency, the Cloistered Cleric is superior.
To summarize... Loremaster is just below par for the Core... and certainly much weaker then the variant or the supplement. I'd probably use it for NPCs instead of PCs. But if you really want to play one, feel free. It is, after all, your character.