Oh right, here we are in one of the classic scenario (and if you try the search engine you will find various TL and thread about this argument)
What Blackfox5 wrote was what Vienna was ready to give to Italy for her to mantain a neutrality favoring the CP and while it was not even near to all what Italy wanted still was enough to keep her satisfied and just for remain out of the fray.
But it's not all gold what it shine, there are some little problem:
1) the negotiation, very difficult and very hard, with both side fighting for every inch of territory...litteraly. This bought time for the entente to launch her diplomatic offensive and greatly hampered the work of the neutralist.
2)general lack of trust between the two side. Both Rome and Vienna in the past 15 years had too much diplomatic squabble to be capable to sign any serious treaty very easily and trust the other side to keep her word.
3)The 'payment' was after the end of the war and as said above there were little trust between the two side.
4)It's not that being neutral it's all flowers and sunshine, the commerce reduced, both side trying to get concession (many time bullying the neutrals), etc. etc.
5)The new border was favorable to Austria-Hungary in term of defense (basically Conrad said that he wanted to be capable to retake the ceded territory in hours)
Regarding Trieste, well while it was a too important city/port to give away (the autonomous city line on the concession basically mean some cosmetic concession plus an italian university)...but with Italy controlling Albania there is already the possiblity that she will be blocked.
With a little insight Italy keep her neutrality will have permitted to be the only Great Power untouched by the war at the end of the hostilites and this is a great diplomatic card, expecially when all your neighbours are embroiled in the postwar internal problem. Italy will have probably extrated some other concession to both France and A-H (if things are kept on the very reasonable both nations are too weak, tired and full of internal strife to oppose it).
Internal change for Italy? Well, more than a million of death noth happening (not counting the wounded), no crippling debt, no infrastructure destruction on Veneto, no general disillusionement with the Liberal goverement and the rise of fascism and communist (sure there will be still a period of political violence but will remain manageable) and the economic boom due to the war will not last much (but it will be much much better than OTL), the colony of Somalia and Libya will be pacified much earlier.
Unrelated foreign change? Switerzland will have her general situation greatly improved as there is no need to guard her southern border and can commerce through Italy. Abyssinia is in the middle of a civil war in 1916, while none in Rome had plan to invade, the situation can explode beyond everyone control (and Giolitti can use this to keep the interventionist occupied).
War related change? No Italian front, Otranto barrage much more difficult, rescue the Serbian Army much more hard as no italian ships and no possibility to use South Albania, Italy as a leak on the blockade, France capable to keep hire italian seasonal workers, no British loan to Italy and no troops send in Italy after Caporetto (sure only 7 division...but they can become precious in certain circumstance).