Sorry for the delay, I have not read a great deal on this and by no means an expert, so this is very much an outline.
SS Unit quality fluctuated over time, and was highly variable within the organisation. Their best were very good.
Their worst were very bad, in several senses of the word
In the early war they were not very important numerically, nor very good. Recruitment had to be carried out against the obstruction of the other armed forces who jealously guarded their "rights" as the sole bearers of arms. One of the reasons the Heer supported Hitler in the Night of the Long Knives was because Rohm and the SA were agitating that they would be the new army.
However, in an army that was short on motor transport what SS units there were motorised and as such of interest to the high command. However they did not distinguish themselves in the War in the West.
