I bought Substance Painter the moment it became available, but waited until the 1.3 patch to review it. I keep trying to use it for texture painting game assets, but the lack of basic navigation and painting features keeps me from being able to use it for anything other than niche projects.
For one, there's the lack of 3D mouse support (like the 3DConnexion). We've asked for it over and over, voted for it, and posted about it. While other feature requests will at least get a response from the development team, this feature is always ignored. At this point, I've given up on ever getting 3D mouse support. So that means keyboard navigation, or remapping my Wacom pen to do middle mouse clicks. But even then, the navigation is clunky because it always pivots on the model's pivot point in an odd manner, making it impossible for me to get into tight places and do texture painting.
There always seems to be some breaking bug with this software. Currently, if you're working with a large-ish model, you'll get a white screen overlay sometimes. It just happens at random times, and makes it really difficult to see what you're doing - much less work with colors in any way. Before that, there was a tangent mismatch with normal maps that was causing obvious seam issues in the viewport. This wouldn't be a problem if the software was labeled as Early Access and priced appropriately, but it's not considered by the company to be Early Access, and it costs $150.
As far as painting, it doesn't have basic tools like smudge/blur or spline/line tools to help with drawing things like seams and stitches. Without these, I have to freehand everything and hope I get it exactly right, otherwise I'm redoing it.
I think Substance Painter works best if you don't actually need to paint. When you've already done all of your model's surface detail in ZBrush, projected that onto a low-poly model, your UV shells are perfect, and you just need to generate some substance-style noise/grunge on the model or stamp stencils/greebles on it, Substance Painter works very well.
So for me, as the product is right now, I can only use it as a limited grunge/stencil adding tool. I have to do all my actual texture painting in another tool. For that reason, I can't recommend it as a finished product at the asking price.
To help anyone reading this review, I've figured out how to navigate with mouse and keyboard into tight spaces - when you hold down ALT and left-click to rotate, make sure your mouse pointer is over the geometry you want to rotate around. That seems to change the pivot point to the geometry under the mouse cursor. Very nice. I discovered this by accident, I searched and searched and was not able to find any info on this. They REALLY need a good help system, like Mudbox, which has 1-min videos that show you how to navigate and paint right off the bat.
If they will implement a smooth tool (like every other painting application), I may change my verdict to "recommend". I REALLY want to like this software.