Don't get too excited over Walmart's (WMT) - Get Report better than expected first quarter results. 'The main thing Walmart has [over rivals Target (TGT) - Get Report , Macy's (M) - Get Report and Kohl's (KSS) - Get Report ] is that it derives a significant amount of its revenue from groceries and that has really helped to keep the wolf from the door,' said Brenda Kelly, head analyst at London Capital Group. That said, Kelly said the U.S. retail sector is still choppy. 'It will be something of a stock picker's market,' she said. TheStreet's Scott Gamm has details from Wall Street.