As a retailer i have used actinic, interspire, oscommerce and am soon to release a magento store.
Interspire i believe is now retired and their support for the product was rubbish which was such a pity as it was so easy to use. Actinic are well behind the curvea nd the software was very buggy. oscommerce was a pain but magento i have found to be really versatile and really not so complicated as people say to use.
You can have a designer re-skin it from scratch, buy a template or buy a template close to what your looking for and then just get it modified - this can save a bit of money. There are loads of extensions that are quite simple to install using Magento connect .
The only downside is it is resource hungry, you'll need a dedicated server to really give it the juice it needs and for us the order processing was hideously longwinded - but there are extensions that can help abbreviate it.
One of the hardest things for us was finding a cart that ticked all the usual boxes but also one thats workflow somewhat resembled ours - you don't want to reinvent all your warehouse pick-pack procedures just 'cos your software says so!
Anyway that’s my personal take. HTH.