Very. It's extremely tourist-friendly. With the exception of grocery store cashiers, everyone I interacted with spoke at least some English.

40% of their "exports" is tourism. There was exactly 0 times when English was not enough.

Like everyone else said, it's easy. We had 2 people who didn't speak perfect English and one could understand us, just struggled speaking it, and another just straight up didn't speak or understand English.

Went to the witchcraft and sorcery museum and the girl who was working the counter spoke perfect English and even sounded American and she said to us "Oh Americans, where ya from?!" and we told her and she goes "Oh cool, I'm American too!" and we followed up "Oh cool where you from?" she said Colorado, then laughed and said nah she's Icelandic but loved pulling that joke on Americans.

Most everyone speaks English fluently, it'll be like visiting the UK.

super easy. my wife and i honeymooned there in 2016. it took three days worth of driving the ring road before we met anyone who didn’t speak english.

Yes. Do it, you won’t regret it