Too many problems
Infrastructure is weak with terrible city government not doing anything to improve it. In recent years so many people have moved here and there are a number of big problems with the roads, public transportation, housing (lack of rent control, predatory landlords, no legislation, etc.), homelessness, drug abuse, etc.
The culture that made Portland cool is no longer as prominent as it once was. With such an influx of people moving here, chasing that cool vibe, the city has become much more of a melting pot of white people. A lot of people moved here from northern California fleeing their terrible cost of living only to increase the cost of living in Portland.
The urban boundary means that Portland has to build up instead of out. This means housing costs become more and more expensive as the only places to live are brand new inner city high rises. The suburbs are cheaper but because the city can't expand they're also increasing in cost of living. Since the highways are intended for a small town, not a big city, living in the suburbs and commuting anywhere is a gamble.
The city is the whitest in the country. While this might not necessarily seem like a terrible thing if you're not racist, there is a lack of diverse culture. Living in a bubble is a great way to become narrow-minded. There are also a lot of hipster social justice warrior types who permeate the cultural zeitgeist here. If you're not prepared to change your views and accept theirs get ready for an earful. White privilege and gentrification are two of Portlands core tenets. Oregon was once a haven for KKK and other white supremacists. This is still quite evident outside of the city. Most of Oregon is pretty backwoods with the Willamette Valley being the only saving grace.
It rains a lot in Portland but not torrential downpours. It just rains often and is always accompanied by overcast clouds 9-10 months out of the year. The "winter" of 2016-2017 started in October 2016 and ended in June 2017. It rarely gets below freezing but when it does the city gets ice and snow and nobody is prepared to drive in it. The city shuts down in the snow and ice. Most of the winter is 40-50 degrees and dreary. The days are super short in the winter compared to cities further south.
The homeless population has boomed in recent years. Some argue that it's caused by lack of rent control and increasing cost of living. Some argue that it's caused by all the safety nets in place in Portland for homeless people and they're coming here from other cities. Being homeless in Portland means you get fed, clothed and shelter provided in the form of shelters or free camping gear. Drug addiction, disease, and mental health issues are prominent among the homeless population. This puts stress on the police and social services which stretches them thin while the local government doesn't do anything productive to fix the situation. Portland police have a bad reputation and a history of applying excessive force on the mentally ill. There have also been known white supremacists on the force.
TLDR: The weather sucks, the people used to be cool in Portland but now they suck too, the people outside of Portland have always sucked, the government and infrastructure sucks, drugged out and mentally ill homeless people are everywhere, it's expensive, traffic sucks and it's getting worse every year.