Presentation: Is using cartoon slides un-professional or fun?
In general, the person talking to your slides should be you, not a cartoon character. 

Now, I've seen things like this work for people who are very good presenters and stage performers as well. For example, one of my grad school compatriots was also a serious performing storyteller, and he understood the performance aspect well enough to do all sorts of fun, risky, and showy things in his talks.

If something like this isn't already you, however, then I would advise not trying it for the first time in a potentially high stakes presentation like this. Conservative may be relatively boring, but it's also safer, and it won't be boring, if your material is good.