I've seen a few people mention that DA:O was competent in all aspects, that it was overall a solid game that didn't get anything completely wrong, but I see it as a game that didn't really do many things right either. We've already discussed the combat so I wont go back to it, but I found the character development pretty bad as well since skills and abilities are so unimaginative, the spell selection is so limited and your attributes get so inflated so fast that putting one point somewhere makes no visible difference after you've gained a few levels. That still wouldn't be enough to ruin the game, because some of my favorite games have worse combat and character development. DA:O just doesn't really shine on any other department either.
The quest design is just terrible. Most actual quests in the game are linear as hell and make you run from one cutscene to another. You may get to make some pointless choice at some point (most likely at the very end of the quest), but that's about it. Then there are the utterly mindless "collect x things of boredom" quests that make up a majority of the game's side quests. It's just inexcusable. The dungeons are incredibly repetitive, partly because of the level design and partly because of the encounter design, so going through them isn't much fun either. Most of these same flaws are present in, say, KotOR (except that it didn't have those horrible filler quests), but even that game stays enjoyable because it has a pretty good pacing between combat and dialogue, and the locations are usually pretty small so that you can go through them pretty quickly before getting bored. DA:O's pacing is just terrible, and for every interesting piece of content you get hours of trash mob fights against the same three enemies. There's about as much meaningful content in DA:O as there is in Mass Effect, but it takes three times longer to finish the game.
Some of this might be salvaged with good writing, but... no. The dialogue is at best decent, at worst it's gay elves talking about their leather fetish or something equally retarded. What kind of a world do these characters live in? Why does everyone want to have sex with my character who is a total asshole anyway? At times you get a good piece of dialogue, but inane banter outweighs it ten to one. The characters are walking fantasy/BioWare clichés. The first actual recruitable NPC is Carth Onasi / Kaidan Alenko with a lower IQ and worse sense of humour. You also have a slightly less innocent Imoen, a morally questionable warrior with an exotic background (basically exactly the same character as Urdnot Wrex and Canderous Ordo), a dwarf fighter who likes drinking and so on. Loghain is the worst villain I've seen in a BioWare game and basically a total clown who is hard to take seriously at any point of the game. He keeps shooting himself in the foot all the time and never comes off as the military genius the game tries to portray him as. The story follows the usual BioWare pattern so closely that you'll know the place of every plot twist before you've even started the game, not to mention that the story itself is as generic as it gets. When you open up the dictionary and look for the word "bland", there's a map of Thedas right there.
I guess you also have to give credit where credit is due, though, and I really liked the origin stories. I only played the Dalish elf one so I don't know about the rest, but I thought it was more interesting and better written than the rest of the game despite the fact that it was a really generic story that has been seen a million times (a kid finds a mysterious artifact from mysterious ruins and then has to leave his village to save the world). I also liked most of the PC dialogue as I rarely felt that my character was forced to say something I didn't want him to say. So yeah, I felt those two things were done right. Other than that, I see it as an utterly mediocre game that really suffers from being too long, repetitive and bland in every way. I think I dislike DA:O for the same reasons that many people dislike DA2, it's just that the first game still had one foot in the closet whereas the sequel is proudly waving the rainbow flag at the head of the parade.