After 100 years as the USA, I came out #1 in everything except for literacy, in which I was 7th in the world. All of North America, South America, all the islands/provinces south of Florida, all the South Pacific Islands, and some of South Africa were under my belt. My GDP was up to 1.9B and had just short of 400 million pops, where 55% of so were loyalists and a handful were radicals. It was an incredible game that I had a blast in.

However, there are way too many points where I was extremely frustrated, got annoyed at the game mechanics, and dealt with plenty of bugs/issues. Here are some of the biggest that I dealt with that made me want to rip my hair out -

1. Reconstruction as the USA is absolutely broken and the most ridiculously vague description of how to complete it. Both my friend and I went through this about the same time (we were doing simultaneous USA play-throughs), I couldn't decrease my radicals to less than .2 in half the lower states, but he was able to get it down to almost no radicals in his country. However for both of us, the states that had radicals down below .2 still had the negative modifier and wouldn't trigger it to be removed. He wasn't even able to complete Reconstruction until it timed out, even though his radicals in each of those states were under .2 overall.
2. Half the time when I tried to do Decisions, the Peril box would just disappear and wouldn't come back until I failed or succeeded the decision. As an example, I was charting the West for the Oregon Trail, Low Peril and at the 25% success point. An event popped up where I chose Minor Progress/Minor Peril and the progress updated but the peril box just completely disappeared. The next time an event came up, it was a Peril option and a Progress/Peril option, chose the Progress/Peril option and it immediately failed me. Decision went away and I had to start over. This same issue with the Peril Box disappearing happened 3 more times and when it did, I just chose the options w/o Peril to try and avoid failing, even if some other options were better but included Peril.
3. AI still feels incredibly broken when it comes to wars it decides to join into. When I went to conquer a few provinces in Mexico, Prussia decided they were going to come into the war as well on Mexico's side. Mexico had no diplo pacts w/ Prussia, I had about 15 infamy overall from a previous war, I had Neutral relations with Prussia, and Mexico didn't call them into the war, Prussia joined on their own for absolutely nothing. How does Prussia decide it wants to help Mexico when there's seemingly no reason for them too and for nothing?
4. RNG roles for laws passing is frustratingly annoying. Way too many times was a stall at 10% or lower or a debate at 25% or lower, yet I still managed to stall or debate a law that went negatively. It took me 5 times to enact Multiculturalism because this happened twice and it dropped it down to 0%. I really hope 1/3 changes law enactments for the better
5. Arguably the most frustrating and troublesome thing I have had to deal with - the game becomes almost UNPLAYABALE after 1900's. The game lags so badly that I can barely do anything w/o a 10-15 second delay. Moving between states to check different stats or upgrade buildings is a major pain and can take 5s or 30s. Trying to war against other nations is so horrendous to the point where I had to pause my game just to deploy my troops/generals onto the battlefield, not to mention when a million more fronts open up (b/c Paradox can't seem to fix that) it takes forever just to move between them and assign generals. My computer is pretty beefy with good specs, no other game has any sort of lag or performance issue (example - RDR2 runs on Ultra graphics and is smooth as butter), yet once 1900's come, Vicky3 gets so horribly laggy

I love this game but I also hate this game. It is extremely fun and very enjoyable to play w/ friends, but playing solo is just a slog half the time and once 1900's come and the performance issues start, I quit the game and don't come back to that campaign. This USA campaign was the most frustrating campaign I've played yet, and even though it was my best, I don't think I'll be playing solo for a long, long time.