i have used wp-ecommerce plugin and had no problems, there are alternatives but they are not free. i wouldn’t look at the rating on it, it has gotten nearly 2 million downloads, i would just try it out yourself and see if it fits for you. but remember you are asking for something for free.
most of those low ratings for wp-ecommerce are given by people not knowking how to work with that plugin and wordpress.
Wp-ecommerce is a very good plugin so just try it.I also recommend WooCommerce plugin but it works just with themes from Woothemes…there are a few very good free themes from them and one of them is http://www.woothemes.com/2011/09/wootique/ .Good luck!
Woocommerce can be integrated into other themes. There are some instructions in the codex on their website as to how to do this. Many of the functions are available as shortcodes so it isn’t necessary to use a Wootheme, it is just easier.
One of the things that you will want to do is sort out what features you absolutely need. If you are looking for a free solution then you are likely going to need something with the large user-base of WP-ecommerce. Woocommerce has the advantage of being the new guy on the block so has been written more recently. It doesn’t have the same user base to have to provide historical support to, but the downside is that there are less users and things like payment gateways or shipping modules to allow for customisation.
I went through an extensive search of ecommerce platforms for a website a few months ago but had to count out many on the shipping modules. They weren’t complex enough or easily customisable enough to work outside of the US (and not using integrated shipping like FedEx etc). I ended up setting up Woocommerce to work with my theme and using the Shipping Table module as a bought addon. Another I set up slightly later was able to utilise a newly published plugin from Codecanyon that worked with the NZ Post API for a purchase of a few dollars. Both these situations allowed for me to stay using a free ecommerce solution and tailor them with minimal money to the websites need.
Free is nice, but you’ll probably have less headaches and hurdles with a paid solution. I’m not recommending any here, but I know from experience the ecommerce plugins you pay for have support, are usually well documented, and very secure.
I’d still say sit down and make sure whatever solution you choose will work for your entire workflow. The last thing you want is to pick a paid solution that falls at the last hurdle or something simple. Ecommerce has a lot of twists and turns and just because it is paid doesn’t mean it will still do everything you need it to do. Thankfully most paid solutions allow you to trial their system for free so you can go through the set up and ensure it does work for you before investing in a system.