Not just over-priced. They are the evil.
I spent over $100 at Magento Go and basically got nothing, cancelled my store 4 days after signing up.
My full story: http://www.kavoir.com/2011/09/magento-go-test-drive-review.html
1. They DELETE your support tickets without responding in any way.
2. They respond to your tickts every 1 or 2 days (IF they respond AT ALL) - simply unacceptable for mission critical sites such as ecommerce stores.
3. There is NO WAY you could delete / scramble your credit card information there, EVEN after you have cancelled your plan. This makes me very very uncomfortable. After submitting 2 tickets requesting my CC to be deleted, it's been over 2 days and they DIDN'T RESPOND in any way.
Oh, and they charge your credit card even after you have cancelled your store: http://www.shoppingcartsforwebsites.com/general/magento-go-review/#comment-469
Horrible story. Do yourself a favor and AVOID them at all costs....