The optical design is powerful and convenient. The long optical tube reduces most image defects, and the 90mm aperture is barely enough for crispy planetary and deep space observations.
The optical tube also has the advantage of overcoming light-pollution and atmospheric effects more easily thanks to its long optical tube.
You can get sharp images of Jupiter and its moons, Rings of Saturn, and with a good eyepiece some detail on Mars. The Moon looks great with AstroMaster 90EQ, but it does with most telescopes anyway.
You can get images of brighter deep space objects such as Pleiades Star Cluster, Andromeda Galaxy, and Orion Nebula.
The optics don’t require collimation or any kind of maintenance. This is especially important for beginners.
Overall the optical design is the best part of AstroMaster 90EQ. It is convenient and powerful enough for decent images.