There are some mechanical issues with the class, like for example all of the types of invocations have been split into their custom ability. While this looks great for organization it is terrible for handling mechanics and comparability with similar types of classes especially if they have other "custom" abilities.
Second the invocations work off of the Warlock level not invocation level. What happens then when another class can increase or decrease this level. Or if other invoker level style classes are added.
It also means there is not way to check for invoker level xxx in the way you check for caster level xx.
Also there is no weapon added to the weapons tab for the Eldritch Blast...
And finally, if this was done, shouldn't it have been added to the C7 source file for tome of secrets....