I really think it has been undervalued both by layman and scholar alike... You usually hear people say the only significant difference is an “addition” to the ten commandments... But the entire thing is actually quite different on many levels, like, for instance, the way it has a much fuller and extended account of Moses speaking the words of God to Pharaoh in Exodus. And now we have Dead Sea Scrolls that are specifically “Samaritan” or “pre-Samaritan” or whatever you want to call them—like 4QPaleoExodusM--scrolls that follow the SP against both the LXX and the Masoretic...scrolls that were used nowhere near Samaria, but by Judeans. It's easy to write the SP off when one hasn't even looked at it. And looking at a few divergences here or there can give one the feeling that we are dealing with one of those “rewritten” scriptures. But until we can look at the thing in its entirety, it is hard to make any real assessment.
It's a real shame the SP isn't translated in English anywhere. I'm almost tempted to do my own English translation and put it up online. How cool would that be...to be the first person in history to translate the whole SP entirely into English?
For those who want to take a gander, the critical edition by Von Gall is freely available online:
He whose wisdom is more abundant than his works, to what is his like? To a tree whose branches are abundant but whose roots are few; and the wind comes and uproots it and overturns it (as it is written, “He shall be like a tamerisk in the desert and shall not see when good cometh; but shall inhabit the parched places in the wilderness"). But he whose works are more abundant than his wisdom, to what is he like? To a tree whose branches are few but whose roots are many; so that even if all the winds in the world come and blow against it, it cannot be stirred from its place (as it is written, “He shall be as a tree planted by the waters, and that spreadeth out his roots by the river, and shall not fear when heat cometh, and his leaf shall be green; and shall not be careful in the year of drought, neither shall cease from yielding fruit”).
--Mishnah Aboth, 3:18 (with Jeremiah 17:6, 8)