Tyranny is quite a bit like Pillars of Eternity, but also significantly different in some key ways. The similarities so far (just cleared the first main quest, annulling the timed Edict) are the combat system, visuals, and acquisition of a Stronghold. The differences are the leveling/class system, magic system, reputation system, and general feel of events.
The leveling/class system is the most striking change. For one thing there are no longer any classes, as instead the game goes the Elder Scrolls route. Your skills increase as you use them, those increases then progress you toward leveling up, and leveling up gives you both a Talent and an Attribute point to spend. You can select any sort of combination of Talents you want from up to 6 different trees (Leadership, Defense, Power, Agility, Ranged, Magic), with the more powerful Talents requiring a greater investment in a particular tree.
The magic system is completely independent of the leveling system, being a tiny bit similar to how Oblivion handles it. You can learn various types of Sigils (base spell type), Forms (target type), and Accents (sundry parameter modifications) by finding/buying them, then using your spell menu you can arrange those components into all sorts of different spells and assign them to any characters who have a high enough Lore skill (more complex/powerful spells require higher Lore values). Once assigned they can be used just as often as any other basic ability.
The reputation system is similar to Mass Effect 2‘s, unlocking new abilities/bonuses for the protagonist as your actions raise Loyalty/Fear with your companions and Favor/Wrath with various factions.
The feel of the game is relatively unique however. Rather than being a random nobody who suddenly becomes great, you’re an already important/influential official who suddenly becomes even more powerful. This has the odd effect of making you not feel very powerful at all… instead everyone else seems strangely weak. You have all these characters who are supposed to be incredible fonts of magical energy walking around and they’re squabbling like children, unable to capture a simple bridge. It’s an interesting choice to make what would be impressive mid-bosses in another game come across like easily dismissable minor bureaucrats.
I’m also a bit turned off by the narrative so far, as the climax of this first scenario came across as exceptionally forced and frankly I don’t much like either side. The Disfavored are your standard rigid knightly group and the Scarlet Chorus are New Vegas‘ Legion. The former seems more or less okay aside from their obsession with purebred lineage and their leader behaving like a child, while the latter is something of a mess whose members constantly want you to fight their battles for them. Neither side gives a particularly good reason to support it (nor for that matter do the rebels).
Well, we’ll see how things develop now that there’s no longer a countdown toward the player’s impending doom. Speaking of, don’t worry about that 8-day countdown. Unless you do something ridiculous like rest after every encounter you’ll only need 2-3 days to clear all the side areas before taking the Spire.