Certainly!
To be Catholic is to be in communion with the Pope, insofar as he " is the perpetual and visible principle and foundation of unity of both the bishops and of the faithful". Thus, all Catholics in good standing with the Church ideally believe with the Holy Father in all vital and immutable precepts of the Faith.
Yet each and every Pope has a whole host of personal opinions stemming from his personal interpretation of the Faith and his own contemplations. These personal convictions, though serving the Papacy and often providing its direction, are not part of the revealed faith and so accepting them are never a matter of faith.
Of course, when the Pope speaks from the throne of Peter to bring clarity to a matter of faith in a manner binding on the whole Church (a dogma), then it is understood that he can not err, for Christ has promised us that the Holy Spirit will lead the Church "into all the truth", that whatever is bound through St. Peter will be bound in heaven, and that the gates of hell can not prevail against the Church.
Thus, when speaking ex-cathedra, the assent of the faithful is required. .
Very rarely does the Pope ever speak in this capacity.