Divine Divinity looks very much like a Diablo game, right down to some of the enemies and death animations, identifying items, waypoints, putting runes into slotted armor, etc., but is much more expansive- based on my own experiences, it felt a little like playing a 2D version of Oblivion, with vast open spaces to explore, guilds to join, lockpicking and stealth, dialogue trees and other similar features.
It's a long, epic game, but that's also its greatest fault- for all that landscape to explore and all those people to talk to, most of it felt very empty and dull, with huge fields full of the same two or three enemies, endless sewers and caverns, and dozens upon dozens of generic townspeople and guards with nothing interesting to say. This feels like a wasted opportunity because the very few quests and interactions you have with main characters (usually those with voiced dialogue) are pretty fun, well-written and memorable, but to get to them you have to slog through tons of foes and minor, less interesting quests which often have poorly-explained goals. It feels like the makers of the game wanted to add a lot of depth with things like a reputation system, overarching quests that can take most of the game to solve, and readable books all over, but didn't quite make it and were left with mere traces of that depth amidst a sea of grinding and map-clearing. The tone is also deliberately silly throughout, ruining any attempt at immersion or world-building.
The game is also a bit buggy and just poorly designed in some aspects, such as the annoying toss-everything-in-a-bag inventory system, at least one quest segment that never gets resolved and stays in your log forever if you do another quest first, legendary magic items sometimes having literally no special attributes when identified, potions of the same type refusing to consolidate into one stack seemingly at random, and the main character voicing some lines but not others, often within the same cutscene.