I have written this to try and provide a balanced view on the plugin for those who come across this thread and are considering wpec. I do recommend this plugin. I probably would not have several months ago but I most certainly do now which is saying something as I am a bit of a perfectionist when it comes to looking after my clients and the technology I use.
I have received great support from Instinct and from the forums. So far (live but not processing live orders yet with PayPal - just at the testing stage with sandbox) everything is working well.
As with most new things there is a bit of a learning curve involved in order to get an understanding of what can and can't be achieved and how to achieve what you want. It is not a magic box that does everything but it is certainly at the point where it covers everything most businesses would need in a standard shopping cart.
Bugs do happen. That is the nature of the beast - you don't get progress and outstanding products with technology without experiencing a few bugs when making changes. The developers at Instinct very quickly sort these where they can if they are aware of them. They also test very thoroughly to minimise these occurrence of bugs and problems. Unfortunately they can't test every single scenario - there are millions of them so some bugs sneak through and it is not until a user experiences problems that they are picked up.
I am not totally sure how forums for open source software are suppose to work. To my knowledge because the software is mostly free, the forums are to provide a central place for us to help each other and a resource for us to look through and find answers to our questions BEFORE posting our questions based on past experiences. It is not something we should take for granted. Most of the support provided, if not all of the support, is provided on a voluntary basis as it is on this forum as far as I am aware. We are lucky and should be grateful if someone does help us out. As far as I am aware the developers from Instinct do try to check the posts but they don't get the time to read everyone's post... something I only just realised recently. They have kindly provided a contact email so if your problem is urgent and you have done the research to try and solve it yourself there are other ways to get help.
One of the best things about wpec is that they are constantly growing and improving... and they really do try and listen to the users and try to accommodate our needs. Again, they can't do everything everyone would like but they do pretty well. I have only been involved with wpec since around September last year and during even that small amount of time they have moved to a whole new level. The resources on their new site are more extensive, not quite there yet but between the documentation and the forum most things are covered and they will get there. I know from experience how long it can take to put together documentation and it usually takes a back seat compared to customer (or in this case user) problems and issues that need to be sorted.
I am not saying the plugin is perfect. Its not but it is getting there. It does work with absolutely no problems for most people. 80% of my problems so far have been because I was just doing it wrong (better documentation would have helped here). The other 10% were because I was trying to do something that you couldn't do and I don't have the php knowledge to hack the code to carry out these more advanced requirements. You can overcome the later if you don't have good php knowledge by employing the services of a php expert. After all, you are building a site to make money, sometimes you need to invest a little in an expert to get things right in order to get maximum return.
My wish list for wpec is:
1. Multi-currency. Instinct is currently granting that wish.
2. More flexible shipping options. The options available should work for most people but they didn't for me. I have engaged the services of an expert to create a plugin which provides the additional options that I require. As far as I am aware Instinct do have on their list to further develop their shipping options but as above, what they have now should suit most situations.
3. Valid code. This is probably the main 'issue' I have now. The code doesn't validate. It took me quite a while to reduce the errors to the point I have. Still doesn't validate but nothing more I can do to fix this as beyond my expertise and my budget to pay someone to fix. This is a big concern for me.
4. More extensive step by step instructions for setting up wpec. From what I understand wpec is easy to set up compared to a lot of other shopping carts but I still struggled with some areas. It was just simple things like doing x first when I should have done y first, or xyz didn't work because I needed to do abc.
5. An area that clearly advises current bugs and tips on things you can't do or things you can do that are not obvious so we don't spend ages trying to figure out what we have done wrong only to find we are not doing anything wrong. I did not come across any bugs but I did come across a couple of situations where I was trying to do something that just wasn't possible but seemed to be possible and DIDN'T come across a couple of things that if I had known I could do would have made my life much easier!
To be absolutely certain that this plugin will meet your needs make a list of your needs, do your research and ask Instinct if you are not sure if it provides certain features you require.
I can assure you the plugin definitely does work. Based on my experience and from reading through the forum when learning how to use this plugin most of the issues were because things were not right from the users end.