I didn't care for Spinoza, to put it simply. First of all, and probably most importantly is, I can't stand fatalism. I hate it in philosophy and I really hate it in theology. Spinoza supports absolute causality. Even down to human emotions. His trivializing of human and divine nature is so annoying and problematic that it is surprising that he became so influential. While he gets some things right that Descartes got wrong (namely, by countering the inane method of Cartesian doubt), he gets so many other things wrong, that I cannot say he was much better than Descartes. I do find it befuddling that often people will cite Descartes and Spinoza as pioneers of modern philosophy. This is a surprising assertion because, firstly, philosophy has never taken a prolonged hiatus since Pythagoras and the Pre-Socratics; it is surprising secondly, because I do not see much that they brought to the table that was new and constructive. I think the people who place them in a unique position in the history of philosophy intend to mean that their output contributed to skepticism and enlightenment notions. I still don't see much that was novel, however. Skepticism was already a component of philosophy. If these same people mean to get across that they beget systems that were not overtly religious, than that would not constitute a first either. Certainly, philosophy, even during the Christian centuries, was never bound to only theological matters. Much of Ockham, whom I've read, was not overtly religious philosophically. So, I definitely don't think that non-religious philosophy started with these two. It might be that they are considered first in developing particular methods and systems. Even here I don't see where they are unique in the history of philosophy.
Spinoza is often called a pantheist; while this is a suitable description to a degree, his pantheism is not consistent and is incredibly problematic. As far as mundane mechanics go, his pantheism works somewhat, although it is simplistic and, in my opinion, silly. He gets into trouble once he discourses on Divine nature. Unity or "pan-ness" is there left at the door and is no longer applicable without issues. Spinoza's god suffers from a fractured nature: his substance is removed from his attributes and his attributes are subject to his nature. God isn't free in Spinoza's system, He is subject to His own nature. This must entail, I suppose, that His attributes and His substance are somehow different from His nature. What we have is a god that is made up of various parts. What his nature is, I can't quite say because I didn't note any discussion of it in here as such. Spinoza believes that the world of causal mechanics shares in God's substance. His argument seemed to hinge on the idea that an infinite substance cannot be bounded, so there can be no other substance save one, and that is God's ultimately. Of course, Spinoza does seem to make distinctions between God's infinite attributes and His substance which must become finite at some point. Spinoza does not elaborate on how infinite attributes/substance can become finite. It seems that at some point, most likely in God, infinite substance becomes finite as thought and extension. All of this makes Spinoza's pantheism problematic. He simply removes a multiplicity of substances from one place, namely, from a mundane mechanical universe, and places multiplicity within God Himself. Regardless of whether or not Spinoza does some sleight of hand and uses different terms to describe God's nature, his god is, ultimately, a divided and multiform god; so pantheism is only a fitting description of Spinozism with very particular caveats and provisos.
I was probably at my most impatient while reading Spinoza's discourse regarding emotions. Here he vacillates quite a bit. All emotions in Spinoza's causal universe are simply reactionary states. Love is both a negative and positive emotion for Spinoza. It's positive when it's intellectual (whatever the hell that means) and negative when it entails compassion and pity, which is usually included in the typical definition of love. I should enlighten the reader that Spinoza is rather adamant about using his own definitions of words. This is something he tries to get across at the very beginning of the works included here. His definitions are sometimes quite equivocal though, so consistency is a problem for Spinoza; especially in his discussion of emotions. As far as love goes, one must note that Spinoza's definition is not only idiosyncratic but pretty ridiculous. He attempts to make love both an emotion and not an emotion. He more than once claims that good and evil are simply pleasure and pain and nothing more. How one can say that pleasure is intellectual, I don't quite know, but suffice it to say that Spinoza's equivocal and ambivalent use of terminology would never aid someone in putting his ethics into practical use. Also, his ethical system is so apathetic that I can't see it being anything but a negotiable and capricious ethics.
Spinoza helped foment deistic thought. So I suppose he holds a unique position in that regard. There was a time when I identified with deism. I now see it for what it is. Deism denies God in practice but accepts Him in theory. Atheism denies God in both theory and in practice. While I think deism is certainly far more intelligent than atheism, it is practically speaking no different; so it's little wonder that deism gave way to atheism during the age of enlightenment. Spinoza is a deist's theologian. Since I left deism a long time ago, I don't see much that speaks to me now in this kind of writing.
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Volume 481 of everyman's Library with dust cover intact.