I've been to the Desert Botanical Garden many times, and each time it gets more enjoyable. When I first moved to the Phoenix -- I was totally ignorant to all the beauty of desert life. This garden has helped me to see the errors of my ways. There is so much variety to be found between cacti and succulents. As well as a multitude of desert critters :)
There are several events hosted throughout the year to make DBG worth revisits -- Flashlight Tours, Jazz in the Garden, Butterfly Exhibits, etc. The staff is knowledgeable and enthusiastic. The grounds are well manicured and well planned out (wide meandering trails, specialized gardens, nice garden shop and folk art displays). It's great for both family and singles alike.
Lately, there has been a bit of construction as they have been improving their garden... but I don't mind, cause its all in an effort to make the place more enjoyable.