This road is OK. It is not a must, it is a fairly nice road to get you across. Rode it in 2008 and due to very busy traffic, I was not able to really enjoy it.
Nice bonus if you are around, but not worth a de-tour.
Nice ride rom Bormio to Livigno along S301 taking in the Foscagno Pass (2291m).
Pleasant ride and at an altitude to get old carbed bangers wheezing.