In 2E, a fighter at first level could take the ambidexterity and two weapon fighting proficiencies and suffer no attack or damage penalties, even if using two long swords. And, that fighter could also be specialized in the long sword at first level. So, he would be attacking 3/2 with his primary hand and 1/1 with his off hand, or 3 times in one round, 2 times in the next round. Each attack could be up to +4 to hit and +8 to damage at first level. In one round, a 2E fighter could potentially do 60 points of damage against a large opponent, or 48 against a small or medium. That does not count any critical hit charts you may have played with in 2E.
So, I do not think the power level has increased THAT much for the PCs. However, I do think that power level for monsters has gone up quite a bit. I know in 2E, we took out powerful dragons at seventh and eighth level as PCs. However, we got wiped out by a mid level dragon in 3E while well over tenth level.
We have hardly any house rules so far in 3E. In 2E, we had pages of them: We now have an official critical hit chart in 3E. In 2E, we used a third party critical hit chart from another publisher.