Critics have consistently praised Klein's work. The San José Mercury News described his performance with Symphony Silicon Valley in 2012 as a “gorgeous performance; big, enveloping and wonderfully luxuriant.” The San Mateo County Times described him in 2007 as “Super Conductor: Mitchell Sardou Klein, music director of the Peninsula Symphony, led his musicians through another triumphant concert. The Peninsula Symphony just keeps getting better and better. Great works and great performances by all.” The Polish newspaper Gazeta Wyborcza proclaimed, “The American conductor quickly established a fine rapport with his orchestra. Klein is a musician who has the musical score in his head, rather than his head in the score, which he demonstrated ably. The creative conception and artistic shape which he brings to his work comes from deep inside him.”