They are simple, very easy to work on, the parts are cheap and easily available. Very reliable if maintained in decent condition and they seem to drive in a smooth relaxed style, the only drawback is that they were not designed for performance and little tuning gear exists...hence they are often replaced by v8s. There was one performance version the OHC pontiac sprint which was basiclly a chevy 6 with a better design pontiac head,4 barrel carb and belt driven ohc. The sprint was fairly quick but also thirsty and the sales were not great so it was dropped in the 60s, if you want speed a sbc is a much better bet but if economy matters then the chevy straight 6 is a good engine.