The temptation seems VERY well done compared to what we have in EA. But I really hope the consequences are huge.
I also want to be rewarded for playing "good" characters and I would HATE to feel that my characters are so much weaker during an entire playthough if it is just about happy / unhappy ending.
There will be a disparity in personal strength between evil and good playthroughs but this is by design. You can choose to go evil and you will end up vastly more powerful but alone vs if you play good you won't be as powerful but you'll have a lot more companions, friends, and allies. It will be a very different experience to reach the city of Baldur's Gate very powerful but alone vs being surrounded by allies. This is what Swen said when answering questions about the dark urge though I think that applies to more than strictly the dark urge. So there is an intended balance there...how much will you sacrifice for power. This is very much intended to illustrate a point. If the game handed you the power anyway regardless of choice then the choice would be meaningless...you wouldn't be inconvenienced in the slightest by just pressing the "do gud" button without a second thought every time. You can be good if you want...but there is a steep price for it just as there is a steep price for going evil as well.
