The merger would be good for GM right now in that they could unload GMAC Financial Services (or more importantly GMAC Mortgage). It would be good for Cerberus right now because they do not really know how to run an automobile manufacturer, but seem to have success with financial services.
Once the dust settles on the deal, it will likely be horrible for GM because they are already overburdened with manufacturing capacity and this will just make it worse. Once the financial dust settles, GM will realize that there were a good many times that they only thing that kept them afloat was GMAC income. Back in the early 1990’s, a disproportionate amount of GM’s income was due to GMAC. Without that, they would have been really hurting.
If the financial markets do not turn around, Cerberus will be caught in a death spiral with GMAC leading them right down the tubes.