I guess the name explain it all , employee in a company always complain that Helpdesk not answering the calls , slow response ..also some installation they need to send a tech support to employee office .
guess what with app portal software , employee will do it by her/him self .
the good thing also it has it is own workflow ,so still Helpdesk or admin to approve or deny , and it integrate with Microsoft SCCM .
this is the future , why to call Helpdesk of you can do it ur self .
now Self Service web or app spreading , and i beleive it is adding huge value .
ya last , SCCM 2012 has it own web for self service but microsoft didnt mention much .