Conjunction is considered a blending of planetary energies. The aspect is considered a neutral one, the quality depending on the nature of the planets involved. Can be used with planets up to 8 degrees, with the involvement of the Sun or Moon, up to 10 degrees. With the Sun and Moon, up to 17 degrees.
Some conjunctions can be pretty difficult. Mars/Saturn; frustrations. Venus/Saturn, difficulties in love, Mars/Pluto, possibly explosive temper. Saturn and Pluto conjunctions can be frustrating, or obsessive.