I played for about 5 hours and had a great time, but I think the "this is the true incline, truly old school RPG with great new features" thing that's going around the Codex is greatly overstating things. It's a lot of fun, it looks absolutely gorgeous, the writing is very good and the game bleeds atmosphere. I spent a long time in character creation and it was very fun to explore all the different character options. And the only bug I've run into is that sometimes the option to lock the mouse to the window stops working randomly.
Combat is usually fun, however I don't enjoy it as much as in the IE games. The main culprit here is engagement. Maybe it gets better at higher levels when you have more characters with abilities that bypass engagement, but right now it makes all combat play the same. Engagement attacks hit too automatically and do too much damage, so that there's almost never any incentive to move your character once they are engaged. Just pound the engaged guy to death and then go engage another guy, pound him to death, repeat.
Encounter design is also pretty lackluster. At first I thought maybe this is just an issue with the low level of the campaign so far, but frankly BG1 still had some memorable encounters right off the bat (the assassins at the Friendly Arm Inn and in Nashkel, the Ogre in the wilderness outside the Inn, that crazy Cleric near Beregost). So far in PoE the only thing that seems to determine whether an encounter is difficult or not is the presence of shades (with the exception of the bear cave). Too few unique encounters + most of the non-unique encounters being against trash mobs greatly decreases the enjoyment I'm getting out of combat, and when you add engagement onto it the whole thing feels like doing the exact same encounter over and over again, using the same tactics. I had enough of that in DA:O, thank you.
The game definitely has time to get better, but so far I think the claims of PoE not simply matching, but improving on the IE games are coming from either people who didn't like the IE games in the first place or folks who are too hyped by a fantastic-looking, well-written game by Obsidian to see its flaws.