"Lukaku is a handful for everybody," Long told the WBA website.
"He's still only 19, he's strong and quick, he's good in the air and can finish with both feet.
"He's near enough the complete striker. He's still young, still learning his craft, but he's a big addition to our team.
"Chelsea sent him out on loan so he can get some experience.
"He cost £18m so they wouldn't have spent that money without having something in mind for him."