I have 3y 11m between mine. They get along well, though there's definitely been conflict and rivalry despite the gap. DC2 is 18m and DC1 is 5, and DC1 needed time to adjust to not being the centre of attention as an only, and having another child in the house messing up her toy arrangements. They do adore each other and make each other laugh, and it's lovely when they find an activity that they both enjoy (sand play, swings, swimming and soft play all work really well). In time I expect they'll be able to enjoy more of the same things together, but at the moment there are more things that they can't do together - DC1 does lots of extracurricular stuff which DC2 is too young for, and DC2 does lots of toddler classes while DC1 is at school.
At weekends DH and I take turns with each DC as they have different needs and interests, even in the same place (eg different playground equipment, toddler area at soft play, funfair rides). In school holidays it was harder with just me looking after both dc and I end up having to ignore the older one for a bit (she often likes to have an adult to play games with her), as the toddler needs constant supervision.
I loved the baby/toddler years and I'm happy to be stretching it out with DC2 - she gets one to one attention heaped on her as DC1 did as a toddler (while DC1 is at school), which I think is better for her development than if we had a small age gap.
I do find it hard to understand how dcs with that age gap can be best friends and play together in future when they're at different stages - the younger one won't have the ability to join in so many things like board games for years, and especially for more formal activities with age restrictions, eg holiday camps, sports and clubs. But it might turn out that they have entirely different interests anyway.