While I think that I support Mt. Gox at this time, pending any major disclosures of facts, a totally new site may NOT be a good thing. I know these guys are working their asses off right now, but it's not easy to test something that comprehensive in a few days time.
Sometimes with code, the simpler it is, the better . I highly doubt they are overhauling their ENTIRE system, but a new look is normal for company's who through periods of bad P.R .This hacking will only make this community stronger, and maybe people will finally realize that this currency is here to stay.