The power of Oracle seems inversely proportional about how wide you can go. Smaller empire will gain more from it. Pyramids is the opposite: more powerful if you have a big empire. All the Production you do not put in the Settlers / Military because you know you cannot spread safely, must be used somewhere.
Pingala/Oracle is stronger in a populous cultural city. More population = more science and culture, and more districts = more great people point. But the power of Pingala do not stop here: a lot of wonder also give additonnal points, allowing Pingala to shine even more. Those wonders are mostly the arts slots wonder*, which synergise really well with Pingala even more because one of his Title can also double the Tourism output of arts.
Basicly, Oracle is at the start of a powerful style of playing. If you build it but not use it efficiently (putting the Government Plaza and Entertainment Complex that yield no GPP instead of Campus and Theatre Square, not getting Pingala and do not go for Grants, do not build wonder that give the additionnal GPP in the Pingala city...) then the Oracle seems kind of weak.
* list of all wonders with additionnal great people points : Broadway (+3 Writer/Musician), ASRS (+5 Scientist), Sydney Opera (+5 Musician), Bolshoi (+2 Writer/Musician), Big Ben (+3 Merchant), Casa de Contratacion (+3 Merchant), Hermitage (+3 Artist), Oxford (+3 Scientist), G. Zimbabwe (+2 Merchant), Terracotta Army (+2 General), U. Sankore (+2 Scientist), Arsenal (+2 Engineer), Alhambra (+1 General), Colossus (+1 Admiral), G. Library (+1 Scientist), and the G. Lighthouse (+1 Admiral).