Nice one and love how they look over the ridges, really natural. Also great they have white backing, this is a must for graffiti.
I'be been using lots of decals on my Cyberpunk scenery and it works well for the bigger images and tags. For the smaller tags I went to the local arts & crafts store this week and bought several acrylic pens by Molotow. Here's a shot of my first attempts on my new Antenociti Cinder block walling. It works really well! Super opaque, easy to use and as it is paint you can use a brush to add some streaking. Really fun and fast to work with.