I feel like not a lot of attention in popular history is given to how people lived in the interwar period in places like Poland or Czechoslovakia. Was it overall a good place to live, or were there problems for people living there?
Like any answer, this really depends on the specific era, location, and type of person you are looking at. An ethnic Pole living outside of Krakow is going to have a very different experience than a Jewish merchant in Lodz, or a Ukrainian farmer near Lwow (modern Lviv).
The Second Polish Republic (as this state is often referred to; following the Polish-Lithuanian Commonwealth of 1569-1795, which while an elective monarchy was known in Polish as the "Rzeczpospolita", the phrase used by Polish states since 1918 as well) was a very diverse country. Unlike modern Poland, which is 97% ethnically Polish, the Second Republic was about 60% Polish; the rest of the population was comprised of Jews, Ukrainians, Belarusians, Germans, and Lithuanians. The territory was also quite different than modern Poland: the 1921 Treaty of Riga, which ended the Polish-Soviet War, saw Poland occupy large parts of modern Lithuania, Belarus, and Ukraine, while territory in the west was still part of Germany. Gdansk, the major port city on the Baltic, was also not part of Poland in this era, instead being a "Free City" nominally controlled by the League of Nations (and being over 90% German, another thing that changed post-1945).
Having been re-established after 123 years of occupation, Poland faced a lot of issues at first. The most obvious thing was how to unify a country that had previously been divided amongst three empires who had largely tried to eradicate Polish culture. That the bulk of the fighting across the Eastern Front had taken place across Poland also didn’t help, as many regions were destroyed over the course of the previous 4 years. Subsequent conflicts with its neighbours (the aforementioned Polish-Soviet War being the most prominent), also meant it was not until the mid-1920s that a semblance of normalcy began to take place in the country.
Now that said, what would it be like for someone living there? If you were a farmer or peasant, regardless of your ethnic background, it would have been rough, as it was in any area of interwar Central and Eastern Europe. Illiteracy was a major issue, though the government did make schooling compulsory, and by 1939 it had dropped considerably. This was still an issue for the non-Polish peoples though, as education would have largely been in Polish. But that was also a factor: despite being one-third of the population, non-ethnic Poles faced discrimination from both the government and from Poles, which led to distrust and conflicts (though nothing serious happened in this era). There would also have been a notable divide among the former Austro-Hungarian, German, and Russian Empires: the people in the former Russian region, especially in the newly conquered territories (like Belarus) would have been even poorer than those in the west (especially in the former German territory). This would not be resolved, and arguably never was.
Within the cities, a substantial part of the population would have been Jewish, which presented its own set of problems. While urbanization was a major theme in this era, with huge numbers of ethnic Poles (and others) moving to the cities, Jews still would have been a plurality of most major cities. Warsaw was something like 30% Jewish by 1939 (I don’t have the number at the moment, but can look it up if requested), and this was a sharp drop from only a few decades ago. Wilno had a Jewish majority throughout this era (or close to it), and Lodz was also about 30% Jewish, while Krakow was about 25%. Jews would have been more well-off than the rest of the population, and comprised a vibrant middle-class. They were also quite assimilated, and many would have been fully bilingual in Yiddish (which would have been used at home and within their community), and Polish (used in public). There would have still been rural Jews as well, who would have been more traditional, but the bulk of Polish Jews at this time would be urban.
Politically it was also a bit of a mess. While nominally a democracy, it was initially dominated by Jozef Pilsudski, who had been a socialist revolutionary prior to the war fighting for Poland’s independence, and became a military dictator until his death in 1935. He had grand plans to make Poland the dominant power in the region, and envisioned a sort of commonwealth of allied nations to oppose (mainly) the Soviet Union, all under Poland’s direction. This didn’t happen, though his people kept control of the government until 1939. They strongly favoured ethnic Poles and the Catholic faith (which most Poles followed), and while they discriminated against all non-Poles, they were notably anti-Semitic, including passing laws of similar nature to what Nazi Germany had initially done (limiting freedoms and the like) Overall though, life would have been tough for people in Poland in this time. As noted above they were literally re-creating a country that hadn’t existed in over a century, and had to also clean up the aftermath of a brutal war. Industry was not a major thing yet, though efforts were made to make that happen. It was tough, and wedged between the Soviet Union and Germany, there was a fear of further war throughout, which of course came true in 1939.
For reading on this era, I would highly recommend a couple books:
God's Playground A History of Poland: Volume II: 1795 to the Present by Norman Davies. This was originally published in 1980, but a revised edition was released in 2005 to update things. It is the definitive English-language history of Poland, and Davies is probably the most prominent scholar of Polish history in English Chapter 18 and 19 are of particular note: 18 deals with the First World War and the efforts to re-establish Poland, while 19 covers the Second Republic.
Bitter Glory: Poland and Its Fate, 1918–1939 by Richard M. Watt. Originally published in 1979 (it was re-released in like 1997, but I have no idea what changes were made, if any), it is the only work I'm aware of that explicitly looks at the Second Republic in English. Watt was not a historian though, so keep that in mind, but it does provide a comprehensive look at the topic.
Poland: A History by Adam Zamoyski. Again, it was published once (in the late 1980s) and updated (in the 2000s), to cover the fall of Communism. Zamoyski comes from one of the most prominent families in Polish history, and has written several books on the country. I haven't read this so can't comment on the detail here, but he is a recognized authority on the subject.
Edit: As nationalities in the region are something I have a focus on, I'll add a couple books that touch on that topic:
And two on the city now known as Lviv (known as Lwow from 1918-39). This is a city that changed rulers something like 8 times in the space of 3 decades, and was a rather multi-ethnic city. Important to both the Poles and Ukrainians, as well as the Jews living there, it gives some context to both how ethnic relations in the Second Republic were, and how city life was in one city:
The Paradox of Ukrainian Lviv: A Borderland City between Stalinists, Nazis, and Nationalists by Tarik Cyril Amar. While this mostly looks at the city during the 1939-45 and immediate post-war era, the first chapter is focused on the interwar period.
Lemberg, Lwów, L'viv, 1914 - 1947: Violence and Ethnicity in a Contested City by Chistoph Mick. As the title suggests, it looks at the city from the start of the First World War to just after the end of the Second. This goes more in depth on the interwar era, and how the city and people were impacted by Polish rule.
For a look at different city, there is a history of Vilnius (Wilno in the Second Republic), by a scholar who has written quite a bit on the city:
I don't know of any that focus on Polish cities, as most histories focus on the Second World War and Holocaust, nor does anything look at the villages and rural life (in English at least; I'm afraid I don't read Polish).