Multiclassing as a general rule sucks
Ther are exceptions but in general:
Multiclassing spall caster is a BAD idea, one less level means gaining your top end spells a level after the BBEG gets his.
Multiclassing fighters iis ok if you multiclass in paladin/ranger/barbarian because you maintain your BAB progression. Barbarian X/ranger 1 is a ncie way to get a two weapon fighting barbarian, for example. Its arguable if this is as good a a straight fighter however.
Rouges multiclass well with ONE other guild, such or sorcerer or ranger to give them a little more oompfh in combat (rogue who can cast truestrike on himslef anyone ? Or manipulate a wand of invisibility without having to roll a 15).
Of course right now Im playing a druid3/necromacer3 Theurge 1, but when the party was formed I was the spare character .. so I had a bit of room to play about
Multiclassing gives better save progression than single classing, but I cant think of any instance this is game breaking. especially as the Paladin save boost got move up in levels
On the whole unles multiclassing is VERY carefulyl though through is tends to dilute a character, so the gain in save progression is relatively irrelevant.
Majere