I have ordered posters from Poster Presentations for every year of graduate school (except maybe one year I didn't have a poster). For all five times, they were super fast and have excellent attention to detail, for example catching 1-2 formatting mistakes and pointing out possible issues printing images that may appear blurry. My work often includes microscopy images, and these always came out beautifully on the professional print format. I always recommend them to my friends and colleagues!
