well if i had the ps cs3 aswell as the bridge starter bundle i would play around with it for a while and see what i could do with it as is.  then since ps is a graphics editing program see how it works with your textures if you are going to make some of your own and then decide for yourself if getting the payed version would 1) save you time in renders, 2) add enough features for your typ of needs, 3) make your life easier while rendering and texturing,  then make your choice from there

sorry i can't be of more help but i figure if you want to form an opinion on something see what it can do and if it works for you cause not everyone is going to like it due to it may not work the way they want it to