No Cusack is not a big problem.
In saying that, from the trailers alone, this one doesn't look like it will have the heart, wit, or even the surprisingly appealing story the first one had. If Cusack would rather produce this film than star in it, it must be considerably weak. If so, then it's a chance for Rob Corddry, Craig Robinson, and Clark Duke to shine in their own movie without a much stronger male lead/veteran actor like Cusack to carry the film. I'm not going to rush to see this movie, but if a friend asks, I won't say no.
"You asked me to find the son of a bitch, sir. I never thought the son of a bitch would be you."