I lived, until last year, for almost twenty years on a small Orkney island. Pros...solitude, if you are comfy with that. Unrivalled scenery and wildlife, vast horizons (I get claustrophobic in towns!), natives with...character....
feeling of freedom to simply live, without anyone breathing down your neck if you don`t fit into the so called `norm`...
slower pace of life, the seasons dominated my working and living and it was wonderful.
It makes you hardy in a very old fashioned, pragmatic way.
There are lots of other `pros` but I`d get boring. I never regretted my life on that island.
Cons..because you know there are some...
Weather, that`s the worst imo...in winter, we could be cut off from mainland for weeks at a time, which meant no ferry or small interisland (Loganair) plane, which means the small hardware type shops run out of all the basics. So, be wise and stockpile like crazy....no loo roll if you have a dodgy tum and none to come for a week or so is NOT fun, trust me!
Medically...(this should have been in the pros, sorry) I found island response to medical emergencies second to none. This is due to the island plane/helo having you in mainland hospital in under half an hour, or further south to one of the bigger ones in a little over that, even in rough weather. Island doctors also tend to take their time with you and are used to the mishaps, accidents and particular island ailments that can strike, and have that frontier type of attitude which inspires trust (unless, like our old doc who retired a few years ago, he likes a dram, and the time you need him, is found to be sleeping a bender off on the nine hole golf course...)
but seriously, don`t worry about medical needs on the whole.
More cons...like all small communities anywhere, gossips can be rife and if they don`t know a thing about ye, they will make it up. That can be annoying, but develop a thick hide, ignore them and you`ll be fine.
Um...can`t really think of any more cons...the pros outweigh them.
Speaking from hard experience, I can heartily recommend island life, it changes the way you live forever.
Hope this helps.