It has the necessary features to be a very powerful application, but isn't very intuitive/user friendly. Also, if using the Express client, there are a lot of reports that you'd think you should be able to export, but they are either unavailable or difficult to access. Again, not intuitive.
Also, updates can take a long time and customer service is not as responsive as you'd expect.
It was also very difficult to amend transactions, sometimes having to delete all subsequent transactions before having the option to edit. In some cases, there is no way to change how an item had been previously set up.
Make sure you get a good implementation team, otherwise your system will always have gaps that will take forever to fix, if you can even fix it.
Epicor Express gave us the functionality we needed to do basic inventory transactions: receiving, inspection, manufacturing jobs and shipping. Can't speak to it's use for accounting but our accounting department seemed to find it sufficient for their needs. My overall impression is that the higher version of Epicor would be powerful enough and possibly more intuitive since it would give you the options you'd expect. But again, their customer service / ticket request process is lacking and I don't think that is dependent on which version is used.