It peaked at number 22 on the Billboard Hot Dance Music/Maxi-Singles Sales chart in the US.

[3] The woman featured in the song's music video is French fashion model Chrystele Saint-Louis Augustin.

Christopher A. Daniel from Albumsism wrote that "Sumthin' Sumthin" is "an inviting track hinting at Maxwell trying to get someone’s attention, filling in the blanks with rhythmic handclaps and syrupy Larry Graham-styled bass slaps.

"[4] Ralph Tee from Music Week's RM Dance Update rated the song four out of five, saying that it is "the most exciting new soul record of the year so far.

While steeped in the tradition of the greatest R&B, 22-year-old Maxwell fuses acoustic sounds with the most soulful of vocals on this blissful mid-paced funk groove that heads straight for the D'Angelo and Don-E market."