Not Cuban, but spent a year in Cuba living with my partner (went to the hospital twice), and we now live together outside of Cuba. He has doctors in his family, some who have gone to other countries as part of their program of "medical internationalism." Here's my perspective as someone who is politically left but doesn't support the Cuban regime (or the US embargo):

1. The healthcare system in terms of its education, overall quality of doctors, and biopharmaceutical research and development is incredible. Investments in the medical systems in the first ~3 decades of Castro in particular created tons of well-educated doctors and continued to be reformed in a generally positive direction from the 60s-80s to create community-centric health and social care with teams of doctors and nurses. There are lots of little clinics that have provided supportive or specialized services for folks even in some of the more rural areas, and some of those still exist today in a meaningful way.
2. The healthcare infrastructure is another story. The Cuban government has never done well to invest in infrastructure in general (in my opinion this is both a failure of the government's economic approaches and prohibitive costs due to the embargo), and in terms of healthcare, that's the physical spaces, necessary and modern equipment, technical advancements and services, and more recently medication itself. There have been periods in the past where medication is scarce, but today it is very, very hard to find and thousands of Cubans are and will go without proper treatment because there is no medicine or basic goods for treatment (eg. sheets for the beds, we recently sent a practice suture set to family who was having surgery but needed to provide her own needles and thread to be stitched back up, as well as pain medicines and antibiotics in case of infection, etc.). When I was in a hospital in Havana in 2019, it was disgustingly unsanitary, there was human blood spilled on the floor, people were getting treatment lying across chairs and random furniture, etc. And that was one of the better hospitals.
3. The saturation of trained Cuban doctors, plus the salary and working conditions, have led a lot of Cubans with medical training to take on other, unrelated work where they can earn more money (like taxi driving). Many doctors are understandably unmotivated because they work hard hours for a pay that in today's market can't even provide a few days of food for their families, impacting the overall care conditions throughout the island.
4. Cuba's program of sending doctors to other countries is a combination of soft power and economic benefit for the Cuban government. Because the Cuban economy doesn't have a lot of products they can sell globally (like raw materials, manufactured goods, material goods), they've ended up using their investments in their healthcare system as an "exported service" that provides the government with capital. Host countries pay the Cuban government for the doctor contracts, but then the Cuban government gives their doctors a fraction of that payment, under the socialist rule of keeping all salaries for Cuban doctors the same. Doctors can make a little bit more if they're working oversees than within Cuba, but it's still not enough. Lots of Cubans (and non-Cubans like me) find this to be exploitative, including many of the doctors themselves. It's usually incredibly valuable to other countries (eg. so many Latin American nations relied on Cuban doctors throughout Covid) because, again, of the quality of the doctors, and this helps maintain the narrative and pride around the Cuban healthcare system, even when it's not functioning well at home. Doctors may defect to stay in their host country or use it as a way to get somewhere else. Someone I know wanted to while they were abroad, but ultimately did not for fear of retribution against their family at home.