I am always happy to see people experiment with builds mixing Divine and Arcane - Always been a fan of the Mystic Theurge but feel the lack of Practiced Spell Caster as a feat has been a problem with this type of build.
Comments to help maybe fine tune your build...
1) UMD - Why? Having Access to Divine/Arcane spells means you will use the level Check system not UMD for your ability to cast the spell. Also with Cleric/Wizard levels the highest you can commit is 11.5 at 20 with the .5 being a waste as all fractions are dropped.
2) .5 on the skills - .5 is dropped at time of checks and only benefits you if you are able to add .5 in the next level. Try to end these skills on a whole number and use the extra point elsewhere
3) Greater Spell Focus Necromancy - Not needed for PrE. If you use the Necro spells a lot its a good choice to help get a higher DC as Heighten will not get you to Level 9 spell casting. However, I think you would benefit more from Quicken.
4) Racial Toughness III - Expensive 10 HP are you sure there aren't better ways to spend the 4 APs?
5) Intelligence vs Wisdom - Why the higher investment in the caster stat of the lower caster class?