As someone who recently made a character with the intent of playing a Mystic Theurge, I have to say that I'm definitely enjoying the various thoughts.

My take on the issue: I've been loving it so far, even though I've not quite qualified for it yet.

I do have a question for the other readers, though: when you take a class that lets you advance in spells from a previous class, is there any particular reason why such classes can't be stackable? I've been looking around for a reason for why that shouldn't work, and I've been inviting my DM to look around for a reason for why it shouldn' work (sadly, we both have a habit of missing key sentences in the middle of rule texts so that we get big pictures but not finer details).

Because what I'd like to do is after getting Wizard 3/Cleric 3/Mystic Theurge 1 is look around at some other classes like the Magical Trickster from Complete Scoundrel or the Virtuoso from Song & Silence (my DM lets us use 3.0 books in 3.5 if we can access them.) The downside is that it'd make me drop down not 3 but 4 levels. The upside is that the non-spell benefits of those other classes could start to make up for it (the Magical Trickster's ability to spontaneously use a metamagic feat once per day can help overcome some of those problems since you don't need to prepare higher-level spell slots with it.)

But, again, this only works as long as I don't find a reason for why those stack, and I'm almost positive that there *should* be a reason for why it stacks.

Either way, though, considering the story in the game, I've been loving the progression to work my way up to the Theurge. The character's RP really makes it fit.