It will probably just somewhat more stable than the French Third Republic, mostly due to the presence of the King and the voting of an equivalent of the OTL Acerbo Law (an electoral law that allowed the Fascist to win enough seat at the election and take control of the goverment through legal means), but ITTL will be a little more fair giving at the winner party less seat or/and needing a much more higher numbers of vote than a filmsy 25%. The most important parties will be the PSU (moderate socialist) led by Matteotti, the PPI (democratic christian), the PSI and PCI (in the end communist and more radical socialist will probably end together), Liberals (remnants of the old enstablishment) and some nationalistic/hard rigth wing/fascist-like party.
Something very similar to the OTL agreement with the church to officially normalize the relationships between the Pope and the Kingdom of Italy will be signed, as Benny basically took merit of the work of others and the talking about this type of treaty started long time before the fascist took over.
Economically things will be probably better as frankly except in their mind Mussolini and co. were not the sharpest administrators and part of their method to maintain social peace was to give at various industries a de facto monopoly/oligopoly that in the long run created a very uncompetitive and obsolete industry; plus there will be not that enourmous waste of resources that were the war in Spain and Abyssinia, not even considering the damage done by the sanctions and the idiotic attempt to create an autarchy.
Socially, things will be very different for the women, even with the PPI (christian) in charges, it will be doubtfoul that they will be totally discarted from the workforce like OTL due to the belief of the Fascist that the woman role in society was only as wife and mother; not due to the fact that the PPI thing otherwise (as they have the same general attitude of the fascist in this) but just because they will just be too occupied to block any attempt to bring woman suffrage to the national stage (in some local election they were already permitted to vote) and because doing a things like that in a democracy is much much more difficult.
The nazi big wigs will find others to use as example as the period really don't lack of authoritarian dictators and Germany will be revanchist regardless of Italy takeover by the fascist.
THere will be a lot of the changes in the foreign politics, as said no Abyssinia war (nobody was really interested in that kind of adventure) and no support for the Nationalist in Spain (at least not at the level of Mussolini) so it's very probable that's the republicans will win...and a later takeover by the communist by force.
Ironically an earlier Anshluss can happen, as in 1934 when Adolf tried the first time if Italy is left alone i doubt that they will do anything except protest and send troops at the border.