I haven't quite finished this epic solo RPG yet, but am confident I can give others a pretty fair rundown on the thing. Bioware spent 5 years making this product, targeting older gamers like me who are fans of the Baldur's Gate and Neverwinter Nights series. And, given that they did so without any D&D licensing, I can say they've done a pretty good job. I'll break my opinions down into categories that really matter.
Characters & Classes:
DAO keeps this part simple - you start off with a choice of 3 races and classes (Human/Elf/Dwarf, Warrior/Mage/Rogue). You gain points per level to spend on stats, skills, talents and spells, but the selection isn't huge and uses a 'skill tree' style of progression. What you do get, though, is the chance to choose specialisations within your class (similar to Prestige classes in NWN). These specialisations aren't unlocked by pre-requisite stats or skills, though. Instead, you have to find a special book or NPC in the game world to unlock them for you. Each of the three classes offers a character up to 2 specialisations, meaning that if I found the right teachers or (very) expensive books, I could make my Rogue a Rogue/Assassin/Ranger, or a Rogue/Duellist/Bard.
Party Play:
DAO is optimised for you to play a party of up to 4 characters (your primary PC + 3 others). You encounter several party NPCs along the way, allowing you to build a pool of characters to choose from. This means flexibility for different missions (do I take a rogue or another tank?), and even your reserve characters level up while siting on the bench. One thing is definite in DAO - you will not get through quests by trying to go solo. The bad guys scale up to your level too, no matter which quests - or order therein - that you do.
Combat:
It's all pause n' play, though you can't chain series of spells/attacks like in NWN. To compensate for this the game give each character 'tactics slots'. Depending on skill choices and level, the more slots each gets. A tactics slot allows you to set a combat parameter for a character (eg: when ally's health drops below 50%, heal them). At higher levels you can feasibly set 5-6 different conditional actions for each party member, and that's not including general 'aggressive vs defensive' behavioural attitudes as well. I still prefer to micro-manage battles, though, because the fights are fast and furious and demand the type of constant attention no AI can compensate for.
Quests:
There is a main story arc over 4 long quests, with plenty of side quests (both during and in between). The developers have poured a fuckton of effort into the stories and it shows. This is both great and annoying. Why?
Cutscenes:
It feels like half the budget went on voice actors. Seriously, I switched to subtitles after the intro quests because of this. Find a clue? Cutscene. Approach a boss fight? Cutscene. Accidentally click on a merchant or party member? Fucking cutscene. You can skip through the dialogue by pressing 'esc' a dozen times, and you will. Constantly. The worst bit is when you approach big bosses. The game feels that villians should be given equal air time, even when my Rogue is trying to tactically place tanks, mages and archers before stealthily back-stabbing the sonovabitch in the neck. And when this sort of cutscene triggers it automatically undoes all that effort and places your entire party bunched together in full view within a circle of rape-hungry henchmen. For this reason alone I turned off the 'Friendly Fire' difficulty option because AoE attacks became redundant.
Downloadable Content:
This is an inceasingly worrying trend among Western game developers who stole the idea from Eastern MMORPGs and started back with NWN (Kingmaker) when Bioware packaged the best open source modules into mini-transaction products. The first release of DOA comes with a couple of download codes for extra DLC - a suit of special tank armour, and an extra quest that nets you a new NPC for your party pool. Personally I suspect these initial 'freebie' extras serve as a tutorial on how to acces and use the DAO site and it's points based currency system (US $10 = around 600 points, which can be used to buy special quests or gear). There's only one other official DLC quest so far (Wardens Keep), and the cheeky bastards actually advertise it in-game - some dude approaches you with a mission while you camp and tries guilt-tripping you into buying it online. Penny Arcade sum up this encounter perfectly.
Still, gaming communities being what they are, all this 'premium content' stuff was leaked on all sorts of torrents within a few days of release.
Conclusion:
Despite some criticisms, this is a good game for old school, dungeon-crawling traditionalists that boasts 80 hours gameplay (especially if you include the 20 hours of cutscenes). The DLC is okay (Wardens Keep only lasts an hour, but you get the only item bank in the game which is cool), but it's a concept I don't necessarily agree with - decent, NWN-style expansions would be better. Dunno if the game's worth $110 (unlike BG and NWN products, there's no multi-play), but it sure is addictive.