Err... not to be raining on your party or anything, but the biggest issue people seemed to have with the game was its poor performance. And since that was caused by the game's use of an unpolished and poorly optimized early build of the Source engine, the patch doesn't fix it. Lots of people (myself included) reported the game suffering memory leaks, too.
<{POST_SNAPBACK}>
Game ran fine for me....but I did upgrade my computer specifically for Half-Life 2.
Athlon XP 3500+
1GB of RAM
Radeon 9800 Pro.
*zoom zoom*
No performance problems at all
In fact, I never really had a hard time playing it for really long periods of time...although there likely is a leak somewhere, as performance did begin to degrade (particularly loading times), but I was already on the third part of town before that happened!
Haunted House = teh