Yep . the first 3 ones of Viper are great . Than , after that , they released 2 extremely weak albums where they where experiencing with styles that where completely alienated from their original audience (which was a Power Metal and Traditional Heavy Metal one)
They reunited "somewhere" in the 2000s and released a "return to roots" album called "All my Life" , this as far as I know is recommended for the Power Metal fans of the band , altought it's HIGHLY underrated because the line up was missing many of their classic era members .
But Shaman is a band to be checked out , I´d say they are somewhat close to Angra in style , but heavier and a little more aggressive and in your face .