Generally the Honda Insight is pretty reliable and we've not had many issues reported: www.honestjohn.co.uk/honda/insight/good

That said, the Insight was pretty underwhelming when it was new and time hasn't helped. A Toyota Prius is a better all-rounder and, as it sold in bigger numbers, there'll be more to choose from on the used market. They're popular with taxi drivers, though, so look out for signs that it's been used for private hire.