Pros:

Nice, I like how virtually all of the mutations created are right on the menu screen and playable.

Cons:

Menu is really unorganized

Conclusion:

Perfect, except that I'm one of those people who like to have everything organized... 
Maybe you could have a menu selection called "Mutations" and have categories such as "Solo Mutations" or "Versus Mutations" inside of the Mutations selection in the next update.