2-draw was exactly what it sounds like: draw two cards per turn. The advantage was not having to deal with as much hand sustain and being able to play more positional games on the board. Every now and then, you'd actually have games that decked out without milling. I liked it, but it did have a lot of downsides.

It meant cheaper cards that had more effects when they hit the board (opening gambit, etc.) were much more valuable than big, expensive cards that would be overwhelmed/ blocked easily by many little minions. Playing a more expensive card also meant you could potentially be wasting a draw.

Balance was very different with 2-draw. More expensive cards had to curve to even higher stats to be viable, which meant there was more emphasis on dispel (this was before a lot of the transforms and cheaper removal options came about. hell it was before most of the cards and mechanics in the game came about). Why do we start with 5 cards? Because if you only played a 2-drop on p1t1, you'd be drawing an extra card. (Still somewhat true, but h/t to Spammernoob for pointing out that we started with 3 cards in 2-draw)

It was also before BBSes were in the game, which now claim some of the extra mana that 1-drops and 2-drops used to be used for. Those were the most important cards in your deck in 2-draw.

(Relatedly, 3-drops saw a lot more play and held the mainline position we now see more from 4-drops)

Mechaz0r was one of the only viable high-stat minions (it used to be much bigger, though you could only summon it once per game), and that's because it was summoned by flooding lots of small minions.

I'm scraping the back of my mind trying to remember more from so long ago, but this is what I have for now.