i'm using prestashop for more than 3 years, using free premium plugins. first time using ps13 and now using 144. condition nowadays much better since the forums is crowd and you can get enough support from there.
latest version is 147, but i cant give you any reviews about that. standard theme is little bit ugly, but working good. that's why i always install premium theme. implementing premium theme always need a lot of effort since many visualization issues like unworking sliders, pictures did not show etc etc. but after running, it's good system. It's stable.
Version 144 come with smarty, but this make web loading become slower.
If you want to implement this, I very very veeery recommend you to test it using localhost first before uploading to your hosting. make sure all function working. i disable cache because it makes paypal payment not working.
I still use is until now and working good. I don't want to change into another system until i can make sure to get better (& free).