Well worth the money, if you have any doubts, I suggest heading over to the website and spending a few hours on the trial version, I spent 9 hours straight on this program playing with the tools and have created a master peice for my 3D model.
One of the best parts is, is it will merge the generated normals and diffuse textures together with your original maps nicely in the end result.
The indie liscense agreement is brilliant and usually by the time you've begun generating $10KUSD per year you'll more than likely be able to afford the commerical version, the comerical version is discounted by $150 if you already own the indie version.
There are however some brick walls you may encounter along the way, if you're reading this then I shall explain how to do some things alot of you will more than likely want to do;
Applying a pre-made diffuse (something you've already created to be edited) Head to layers and create a new fill layer, put it on the bottom then go to file>Import images>import your diffuse, the diffuse should show up in the decals tab, drag and drop that on the bar that holds the 'color changer' and it will be applied.
With the normal maps, it gives you an option when you load a custom model to add pre-made images, in this section you would've added your normal map, if you have done this then on the left hand side there's a window with undo history and material information, scroll down to Additional Maps and click on normal map and apply your normal map.
Turning off seamless texturing; while you have your brush selected go to the right hand panel that holds that information, click on the stroke and the advanced options will show, set the alignment to 'UV' to stop the annoying bleeding, this is good for painting only on the 2d view.
As of current, as far as my knowledge goes, you can't turn off the gloss/specular in the 3d viewport, there /might/ be and option somewhere though, there isn't a whole lot of documentation on Painter and the official tutorials are out of date.
I suggest you copy and paste this info somewhere, it may be useful to you because it took me a little while to figure it out and find the info on it.