Gestalt (A Mystic Theurge Monk?)

[Haveatya]

10 Empyreal Sorcerer , 10 Theurge on one side with 10 Cleric and 10 Monk Unchained on the other.

All wisdom casting, spontaneous casting arcane isn't harmed by dips while clerics know all spells. Full level 20 casting in arcane and divine with a pretty safe unarmored chassis, incredible saves, good AC, and good mobility. As a kicker you could use VMC magus for fun.

Am I missing something or does this character seem as potent as I think it is?

[TheOneHawk]

I'm assuming you mean Cleric instead of Sorcerer on the second side?

[grarrrg]

Drop 2 levels of Monk, grab 2 levels of Infiltrator (http://www.d20pfsrd.com/classes/base-classes/inquisitor/archetypes/paizo---inquisitor-archetypes/infiltrator) Inquisitor.
Let's you add WIS to Bluff and Diplomacy, so you can Party-face on the side.
Cunning Initiative lets you add WIS (and DEX) to your Initiative roll.
Forbidden Lore allows you to cast spells of an alignment opposed to your deity. This should apply to Cleric casting as well.
Your 1/day Judgement can be used for a +1 bonus to a variety of things.

Your Inquisition/Domain must match one of your Cleric choices however, so this feature isn't too helpful.

[Haveatya]

I'm assuming you mean Cleric instead of Sorcerer on the second side?

Yes, thanks for pointing that out.

[avr]

Theurge classes are often banned in gestalt. Also, you have 2+Int skills for the first 10 levels (when skills matter most) with probably a mediocre Int, and you have a poor reflex save, 3/4 BAB and a d8 HD, and the action economy is nothing special.

Don't get me wrong, it's got potential, but I'd tone down the double-9 casting for something which patches holes better.

[Nashira]

Theurge classes are often banned in gestalt.

This is actually the RAW for gestalt. The idea being that if you wanted theurge you'd just take your varieties casting classes on either side. It's way too powerful if allowed in gestalt.

[Florian]

Gestalt is always crippled by the economy of actions. You don´t gain power, you just last longer.
I´actually always amused when someone tries to reduce gestalt to being SAD, even more so, just focusing it on a single attribute. You create your own personal point of failure in this way.
In addition, the VMC framework excludes regular MCing, why should it be different for a Gestalt?

[grarrrg]

In addition, the VMC framework excludes regular MCing

No it doesn't. (http://www.d20pfsrd.com/classes/character-advancement#TOC-Core-Classes)
It doesn't recommend it, but it doesn't outright disallow it.
"It is probably a good idea to use either this variant system or normal multiclassing, but it's possible for the two systems to be used together. In a game using both systems, a character can't take levels in the secondary class she gains from this variant."

[avr]

Gestalt is always crippled by the economy of actions. You don´t gain power, you just last longer.
Nah, there's plenty of classes which have passive abilities or swift action abilities, or long-term buffs. Cleric // Sorcerer might do well on the last but they lack the first two. Then there's stuff like a maguses spell combat.

[Jack_Simth]

I´actually always amused when someone tries to reduce gestalt to being SAD, even more so, just focusing it on a single attribute. You create your own personal point of failure in this way.Well, yes and no.

Any ability score, if reduced to 0, will render a character paralysed (Dex, Str), unconscious (Int/Wis/Cha), or dead (Con). Most builds have at least one dump score, so anyone can be attacked in this manner; it's nothing specific to a SAD build.

A build for which one ability score is applied to all basic functions of the character will have problems when that ability score is attacked, yes; getting one ability to AC and saves and offence means that attacking that one ability attacks all three, vs. a MAD character for whom it only likely attacks one or two... with the same build resources, the SAD character is usually starting from a better position than the MAD character (it's easier to get higher numbers when you've got one thing to focus on, rather than three) and so while any given hit to that target ability score means more, the SAD character has further to go than the MAD character does.

Moreover, even with SAD characters, the other abilities are not usually completely ignored (well, as long as the things that make the character SAD are additions to, rather than replacements for, the normal ability score to that thing - so the Sidestep Secret from the Oracle's Lore mystery, for instance, is something of an exception), then the normal ability score is still useful, and there comes a point where it's easier to add six points to Dexterity than it is two points to Charisma, and if you're only applying Charisma to three things, you get more bang for your buck out of the dexterity increase.

So while yes, there's a single-point failure... it's always there anyway in some form, and it'll benefit you more than it penalizes you in most circumstances.