I've spent about a dozen hours playing with Make Your Own Maps, and so far I love it! I had some trouble initially downloading the Photoshop files (they are massive), but Matt at Dark by Dezign quickly came to my aid. He is extremely responsive and helpful if you run into issues. As the publisher notes, you need to have Photoshop and be reasonably proficient at using layers in particular. I'm not a Photoshop expert by any means, but am finding Make Your Own Maps very intuitive and easy to use.
The "heart" of Make Your Own Maps is 3 Photoshop maps, each with an incredible number of layers. Simply by selectively hiding and displaying layers, you can modify the existing maps in a variety of ways, creating multiple floors and different variations. You can fill the buildings with furniture, add torches, keep them empty, etc.
It took me a while to get used to working with this many layers, but I created separate Photoshop documents with the items I was using frequently, which made it much easier to access and use them. Many of the items are very easy to modify without needing much artistic ability; I had fun using and modifying a bunch of items to make a medieval/fantasy tavern. It took me several hours, but I made a 24"x24" tavern with a cellar (and secret cultist lair), ground floor, second floor with sleeping rooms, and a third floor attic. The 300dpi resolution is good enough that details are crisp on a map this size, and at this scale it will look good with 32ish mm figures.
A very generous license is included if you want to publish maps yourself using Make Your Own Maps (you can freely publish as long as Dark by Dezign gets art credit). I don't know if I'll try that, but the maps I made (using mostly their items, with a few of my own added) look comparable to many other professionally published maps. It's very easy to integrate your own art given the way these files are set up.
Other than the dizzying array of layers that you need to sort through, this product is very easy to use (again, assuming you are decent with Photoshop layer use). There are a few items that seem out of place considering the rustic/medieval feel: a modern toilet, bathtub, sinks, and beds/bedding are the only options included that I could find. However, these can be modified with a little work. All the walls are wood, which makes sense for the three buildings, but I'd love to see stone walls as well. However, stone walls and some other accessories (e.g., a bar) were easy to create by modifying some of the items included. The grass and wood floors are a bit less "professional-looking" than the other items, in my opinion, but they are still decent. In my opinion, all of the other items that I've used look great, and are comparable to other professional level products.
The price (currently $30) may seem high, but considering the generous license included, this product is well worth it if you plan to use some of the items in commercial products. Even if not, for the quality it seems like an excelent value compared to many commercially available dungeon design programs. If you already use Photoshop to design maps, this product will save you lots of time and will help make them look great.