1 What is the best aspect of the system you currently use?
A mix of seniority and points based to allow a fair and transparent leave system. Those who have a fortnight off in July or August this year will probably have April/May/June/September/October next year. Leave is allocated months in advance so plenty of time to plan. 42 days annual leave of which 15 are allocated to winter leave, 10 are allocated to summer leave and the rest are at the request of the individual to request, or carry your leave into next year (company can allocate some leave though to avoid buying it back from you).
2 What is the worst?
Summer period is April to October so summer holidays with kids can sort of skip a year.
3 If you had a family event to attend in 1 years time, what are the chances that you would be able to get that specific date off?
Nearly 100% you will get the day or days off. Unless its 24/25/26th December!