magento is worth it in the end, stick with it. post up your problems here or in the e-commerce forum and we'll try and help you out.
it just blows everything else away with what it can do and how extensible it is and there's plugins being written all the time.
is it a new install?
no products are showing even though you added them? are you sure stock level is > 0?
404 errors, have you set URL rewriting correctly? turn off url rewriting while in development and see if it works