The combat system is deep, but in my opinion, there's far too much of it. Hours of this game will be spent fighting grunt enemies in long dungeons that you will have no chance to lose against 80% of the time. There's mods to skip the fade and deep roads areas, which are the worst offenders for this. I'd recommend getting them even on a first playthrough, I didn't and I really suffered for it.
Melee classes really aren't fun as their gameplay will mostly consist of watching your character slowly autoattack like their joints got replaced with tar and their muscles have atrophied from a 100 year coma. Play as a mage.

The real strength in this game is the dialogue. The freedom of choice is wider than in any other rpg I've played yet. Especially in the main quests, the variety of what can happen from your choices is impressive.
It's pretty hard to get a very good ending your first time, but that's what makes it interesting. I love Mass Effect, but the dialogue system handholds you, and you can assume the paragon dialogue option will lead to a good outcome 95% of the time. In DAO, being the stubbornly honorable nice guy can blow up in your face, just as it might in real life.

A lot of the flirting dialogue is incel-tier, and I don't think the writers for this game ever talked to women before. I can forgive that though because until ~2014 Michael Kirkbride was the singular game developer in the world who even knew what sex is.

This is one of my all time favorite games and I hope more people will be exposed to it. I played this for hundreds of hours on PS3, and now am racking up hours on PC. If you're an RPG fan who loves player choice, good characters, and a unique story every playthrough you have to get this. Dragon Age's world feels real and well thought out, character creation isn't just an aesthethic choice like in Elder Scrolls with maybe a few greeting lines changed. Character creation in this can change the entire beginning of your game, and give you different insights on things you wouldn't have before. Tons of lines of dialogue are changed depending on your Origin, Class, Gender, and choices. Every Origin has an entirely new prequel mission to play through and they're all fantastic. My favorites being Human/Elf Mage, Human Noble, and Dwarven Noble. But there's others as well, City Elf, Dalish Elf, and Dwarf commoner. This game is fantastic with tons of replayability, a great story, fantastic characters, missions, and locations.