Are melee builds good?

Hello, Im new to WF and was playing with a friend who is far more experienced than me. He was showing me the ropes and how to play, and when talking to him a about the different Frames and weapons and builds, I asked if melee builds are good and he said no that melee is far weaker than standard guns.

Is it true? Because Ive seen some videos of people running melee builds with Excalibur/prime/umbra. And if I were to aim to make a melee build, is it only Excalibur/prime/umbra or are there any other Frames?

My friend gave me a full set of Gauss Prime because he said Gauss is one of the best Frames, will this work as a melee build?