Episode Two more than makes up for Episode One's shortcomings, and managed to find the perfect balance that the ending of Half-Life 2 sorely lacked.
Again, Valve tilts the game in the player's favor by giving you a new deadly weapon capable of decimating everything in its path. When I saw this, I immediately thought of the lackluster Citadel level from the original and began to already mark Episode Two down several points. But unlike the original Half-Life 2, where the grav gun was so skewed in your favor that you practically walked through the Citadel, Episode Two gives you a legitimate challenge. And it's awesome.
The fact that Episode Two also ties in with Portal, one of my favorite games in years, and resolves some nagging plot points while introducing what looks to be a mano y mano, knockdown fight in the Arctic makes me anticipate Episode Three with much frothing. FROTH, I SAY.