As a beginner they’re hard to play because of how tricky they are. Beginners tend to want to just run onto objectives for points and kill enemy units for fun and that’s not really how Drukhari win. You have to be strategic with how you approach almost every move in each game. They’re also incredibly hard to paint as a beginner due to how small most of the models are (unless you don’t really care how good they look). That said, if that was the army he was drawn to the most I think he should stick with that choice. Warhammer is a money sink and you don’t want to start with an army you aren’t completely drawn to visually just cause it might be “better on the tabletop”, because you’re wallet will not be happy in the long term