Full on open source
Good speed
Creating templates is simple using smarty template engine
Fairly easy to upgrade
Many add ons and templates
Back office fairly simple to use
Creating templates and modules requires a small learning curve
PrestaShop Theming Explained here
http://net.tutsplus.com/tutorials/prest ... explained/But PrestaShop having some disadvantages :
1) A fewer number of marketing functions. Prestashop solution lacks features that other mature e-commerce solutions give.
2) Lack of modules. Most essential and important modules for a fully functional web store are very high priced.
3) Support. The community says there's no sufficient support and help on any PrestaShop-related questions and problems.
4) Lack of scalability. Prestashop is really ideal for small stores, but surely matter if you want to use it for full scale shopping web-site. Other weakness is that Prestashop e-commerce software has not the multi-user interface.