do you think it's harder for a .BIZ domain to have good rankings in Google compared to say .com or .org? Does Google, Yahoo and other SEs treat this extension differently since it's more business-oriented?
Yes I agree. Search engines treat all tlds equal. It may be a tiny bit tougher to get links to a biz site considering other people's assumptions about that tld.
SEO point of view, it make no difference. But I think, as per End user point of view, people can more believe on .com and .net extension rather than .Biz or .info extensions.
yes its on top tld. if it is .tk etc... then there is difference. top level tld's are .com .net .org .info .biz