Devil's Lake is a pretty good spot, all things considered. For me though, the hiking around and Rock climbing opportunities were good, but the actual campsites are pretty standard and left me wishing for more tree growth to feel more secluded. But it honestly is a good car camping/family spot. Many young children will have fond memories of their yearly trip to Devil's Lake.
The only knock on this was the showers in the nearest building to our site needed replacement. They were usable, but not really with my 3 year old. Otherwise we loved our large shady site.
The only negative about this super popular campground is that books way too quickly. You can make reservation 12 months ahead of time, and it's still super hard to get in. Close proximity to major cities (Madison, Milwaukee and Chicago) makes this a popular destination. Campsites are pretty private, nestled in woods. Tons of beautiful trails makes it a great hiking destination. Fun place to spend the weekend at, if you are lucky enough to get a reservation.
Our site was in mature forest and fully shaded. There was a lot of space and a decent amount of privacy. The Lake is beautiful and great for swimming. There are boat rentals and many other amenities. There is also a lot of hiking in the area.