The Moon ⧃ Looks great (except of course when it’s near full and shows hardly any shadows or relief), and you can see details on it as small as a couple miles across.
Mars ⧃ Its polar ice cap is easily visible, and when it’s close to Earth you can just make out a few dark albedo features on its surface - along with, of course, any dust storms that encircle the planet.
Jupiter ⧃ Cloud belts and Great Red Spot are easy - and its 4 largest moons (Io, Europa, Ganymede, and Callisto) are visible as tiny dots and silhouettes when they transit/eclipse the planet.
Saturn ⧃ Rings and the gap within them known as the Cassini Division look fantastic. With some effort you can also see Saturn’s cloud band structure and at least three of its moons; up to six are visible with good conditions and a well-trained eye.
Uranus and Neptune ⧃ Uranus and Neptune are nearly stellar dots. Neptune’s moon Triton can just be spotted on a good night with the 150P, while Uranus’ moons are just barely out of reach.