I know I've posted similar to this before but let me contribute here:
Niqab as many Muslims know is a very highly debated topic even among the most pious of scholars. Some truly believe it's obligatory,and some that it's highly recommended. And then you have certain scholars who insist it was only for the wives of the Prophet and not just anyone.
Personally I am with the opinion of Sheikh Al Abani and a few other prominent scholars that is whilst it is a highly rewarding act it is not obligatory. And a woman who doesn't wear niqab is not inferior in her religion to a niqabi because a person's piety and superiority is for Allah alone to judge.
Even if you are to believe that niqab is obligatory it's still not for us to judge who is pious and better a Muslimah and who is not. Cos a woman who wears a niqab and then goes out and spreads gossip and calumnies about others or is an ungrateful wife who makes life for her husband and family difficult, will in no way be better than the lady who doesn't wear a niqab but who guards her tongue and does rightly by others.
Bottom line is a niqab if worn to please our Lord, and gain His reward, and with knowledge and understanding, will Insha Allah gain us some rewards but will certainly not guarantee us a sure place in Jannah. Our ultimate aboard is for God alone to know..Period.