It depends on what you want to do. But it could work. The question is whether or not its worth it.
I'd also do it with the Hellion instead of the witch because it would mix better with other classes. Bonded object (which offers a bunch of useful options) instead of a familiar (that wont scale), better hd, bab wont matter if you just take one or two levels, but overall I think it works alot better for this concept, and still gets the hexes you want.
Familiars scale pretty well actually. The only thing they miss out on would be more natural armor and some points in INT.
After that, it gets half of your hp and the rest is based upon your own stats: saves , BAB, skills, etc.
The familiar is particularly useful if you get a raven, which gains the ability to speak from the get go based upon...one small asterisk in the familiar section. Theoretically it could also be useful in combat using things like acid flasks and your BAB (although that might need negotiation with your GM; I am unfamiliar with the official take on this)
So yes, it seems cool over all with the dip worthy approach. The feral speech hex is another nice hex to get since it doesn't mention any particular time limit on its 'Speak with animals' effect, just a restriction on type you an talk to at once (and that was pretty broad with things like mammals, bird, fish, etc). Useful for interrogation squirrels after bribing them with nuts.