His record is certainly less than stellar. In his tenure in Toronto, the best bat he and his staff have developed (at least that's made it to the bigs to this point) is Aaron Hill. He inherited Wells and Rios. I'll give him credit for a few good trades (acquiring Ted Lilly for Bobby Kielty, Accardo for Hillenbrand, and, to this point at least, Rolen for Glaus). But his MO seems to be to compensate for his poor drafting and inability to make meaningful trades by signing borderline veterans. Some work out (Matt Stairs), but most don't (Ohka, Thomson, Zambrano, Benitez, Stewart, etc.)
Perhaps the best indication of Ricciardi's questionable talent evaluation skills lies in an inexamination of the people he didn't bring in (for big bucks in most cases), but reportedly wanted to: Brian Giles, Matt Clement, Adam Kennedy, Gil Meche. He also chased Brad Wilkerson and Kevin Mench as free agents a couple of years ago, but was outbid (he since acquired both when they were cut by their incumbent big league teams). If he had signed even a few of those guys to the deals that he reportedly offered, he would have crippled the Jays' payroll for years and most likely would not have the job right now.