I had a 75 Vega. It was a nice little car, not just my opinion, but those of my import driving friends who took it for a spin. I bought the car with minor collision damage and after I repaired it, I was going to flip it. After living with it for a few days, I sold my 69 Bel Air and kept the Vega. I sold it a few years later during one of the energy "shortages" for more than I paid for it. The car was still in fine shape with about 80,000+ on the clock. Never burned any oil.
I knew several other owners and they were mostly happy with their Vegas. Our neighbor, a fleet mechanic for NY Telephone, bought his daughter one after checking out all the cars in the economy class. One girl I knew had a 71 and the engine did puke. The early models had some teething issues that were quickly and effectively addressed.
Back then, it was common practice for car guys not to buy the first year of a new model because in reality the car was still in development in it's rush to the market. This was especially true for cars like the Corvair and Vega which brought new technologies to production cars.
GM faltered again with the Fiero. My brother unwisely bought a first model and had more than his share of troubles. The later models were much improved, but GM had shot itself in the foot again by rushing it's introduction and pinching pennies in development and production and squandering dollars on fixes.
GM excelled in engineering and marketing, much less so in labor relations and ultimately build quality. We all know the rest of the story. Still, the Vega and Corvair were, for the most part, pretty good cars at the time. As long as you didn't buy the model's first year