I was involved in an online business where Shopify was the backbone to the website, it worked well and was preferred to Magento, saying that, I didnt have much to do with the building of it so cant give you any info on the website itself.
Shopify though do take there fees, you have a fixed monthly fee, each item you sell incurs a fee and if the buyer uses paypal you incur a fee from paypal and shopify, its all small percentages but does build up, they also hang onto your money for around 4 days which is then transferred minus the selling fees.
There is lots of add-on apps which are great if they suit your business, key though is finding someone who can edit your site quickly with no problems over desktop/iPad/mobile.