DSLRs have now well surpassed film in resolving power, as well as a few other criteria like noise, reciprocity failure, color accuracy etc. There were quite some heated discussions and arguments about 5 years ago when this occurred. The most optimistic studies put the resolving power of the best (smallest grain) 35mm film equal to 24MP, but most folks who did comparisons found it to be closer to around 12MP. The D800 will be way beyond that in any case. And so it will have the ability to expose even slight flaws in lenses or technique, more so tan film ever could.