We had the most fabulous break there last year. We stayed on Tresco which was beautiful, but Bryher was my favourite island. We got the helicopter from Penzance which was over and done with in 15 minutes - I flatly refuse to go on the ferry, it's notorious for causing terrible sickness.
Be aware, the sea is ICE cold. We went in July but couldn't go in without a wetsuit. I live in Cornwall so you wouldn't think it'd be radically different but it is.
My favourite aspects:
Doing the circular route of Tresco at dusk. We set up camp in one of the castles to watch the sunset. It was very magical.
A wildlife spotting boat trip. Hundreds of dolphins all around the boat, it was insane. Seals in the distance and of course heaps of sea birds
Exploring Bryher, feeling like a character from a Michael Morpurgo story.
Kayaking across from Brhyer to Samson, checking out the old ruins. There really isn't much to see and when I went it was a total wilderness, no proper paths up to them, but it felt more authentic that way.
The icecream. God knows what they put in it but it's the most divine stuff.
The chips at the pub on Tresco. Proper nice. Pizza at the other restaurant was v good too.
The stunning view of the islands from the helicopter. In fact the breathtaking views from walks around Tresco and Brhyer generally.
The chap at the bike hire shop on Tresco. He was really kind and came to my rescue, despite having plenty he needed to be doing!
The sand. It's white and soft, and has all these crushed pearlescent shells in it so it sparkles in the sun.
The feeling of trust. Everyone just leaving their doors open and bikes everywhere.
My LEAST favourite aspects:
The chips at the pub on St Agnes. They tasted like urinals smell!
St Agnes in general. I wouldn't be in a rush to go back there. I just felt bored.
The rats. Not their fault of course but it wasn't great seeing them round about the buildings on Tresco. Some idiots were feeding them!
The feeling of being stuck if you get a ferry over and miss the last one back. I had a lovely guy give me a free ride on his boat when I missed the last ferry.
The expense! Of course it's understandable but it was staggering how much even basic things set you back, never mind souvenirs etc
The dodgy quality of the fresh produce. I guess because it's done so much travelling. I did feel kind of scurvied by the time I was done though!
That's about it I think! It was a once in a lifetime type trip for me, I'm so happy I went.