Augustus brought peace within the war torn Empire that Rome became. He stopped the civil wars and brought with him effective government and programs.
I'll start with some of the building programs he started. As mentioned, he built the theatre of Marellus in 13 BCE, which was the largest in Rome. He also renovated the theatre of Pompey, and he also built the theatre of Apollo. He expanded the water system, and built two new aquaducts in Rome, the Aqua Julia and Aqua Virgo. He renovated over 100 temples (supposibly 82 in one year alone). He had the Horologrium (spelling?) built, which was essentially a big sun dial. And he expanded the roadways.
A couple more things would be the fact that he reformed the army in a major way. He organized a professional branch for the Navy. He created the praetorian guard (debateable whether this is good or not). He also was given the Eagles lost during Crassus' Parthian campaign by the Parthians.
On the civil front, he created a company of 3,500 professional firefighters under a fire chief. He also used much of his own money to fund some of the building projects, and gave money to the state when it needed it. For example, if you read Augustus's Res Gestae Divi Augusti he mentions buying grain for the state, giving money to towns so his troops could settle on land. He also gave money to all of his soldiers (praetorian and legionaries alike) after he died (in his will).
The Equite class benifited greatly from the reign of Augustus, they were offered new offices, specifically for the equite class, such as commands in the praetorian guard, fire chief and other provincal offices, such as keeping track of the grain coming from Egypt.
As for the plebian class (lower class), one of the major problems he faced was the lack of farm land in Italy. He offered them land over sea for farming. He also kept a steady flow of free grain for the Roman poor within the city of Rome itself (sometimes even buying it for them himself). And of course, the creation of the new firefighter company helped poorer folks put out the flames instead of having the whole block turn out with buckets. He made sure that the poorer class always had food on festival days, by food distributions.
He promoted writers such as Vergil, Propertius, Tibullius, Horace, Ovid (until ovid pissed him off) among others and they wrote many master pieces that we still read today, including Vergils Aeneid. Although a con would be all of the writing (most of it) was state controlled and some propaganda.
Another important point was the problem of succession. When he died, he knew there may be problems with who would become the next 'leading citizen' (IE Emperor or Princep if you prefer). He figured that if the Senate simply chose another Princep, civil war might very well errupt again. He figured someone (a general perhaps) might challenge the Senates choice and wage war again. Augustus also thought that if Rome returned to the old republican method of government, corruption would take over again and civil war etc. So he figured, that if he choose the successor, and invested a capable person into the office, he could avoid this, and thats what happened. This seemed to have worked in the case of Tiberius since there was no major civil war. This broke down after a while.
A con i suppose would be his reforms to the justice system. While many civil cases were brought before judges (see my post on praetors). All high level cases were brought before him. He reduced praetors down to mere imperial administrators.