I have played through the majority of the game. If you max out blacksmithing and add 8 points to sagecraft you will be able to construct substantially more helpful equipment then you will ever get with any set.
The sets that are available are not useless BUT they aren't as effective as blacksmithing your own throughout the game. That being said, set items are worth the most when selling and will help a great deal in purchasing repair kits, lockpicks, and potions throughout the game. Even with out blacksithing, there is not a set equivalent to any level that is substantially better than green, blues, and purps that become available. It is also very hard to complete the best sets as some are in special chests and others are drop only and very rare.
I realize i didn't perfectly answer the question. Yes, their are partial and completed sets in the game.