I'm a huge fan of SC1. I Still play it, I'll be practicing extra for SC2.
I really can't wait, seems like a new variety of splash vs swarm and large unit vs sustained attack units. The Protoss WarpRay seems to counter the BC very well, but it looks like it would suck against alot of smaller units.The new protoss mother-ship-thing is very, very cool. I'm mostly excited about the new ablities the units have. The shield that stops missles mid-air, the black hole, and Immortal teleports within pylon range (Makes for badass micro, now protoss isn't as vulnerable to zerlings early on, supposing that this ability isn't a tech).
Not to mention the new protoss shields on immortals, that makes them resistant to hard hitting attacks, so seige tanks and other hard-hits do very little damage. (4Immortals killed 6seige tanks seiged). It says they are weak against many smaller blows, so marines tear them up like butter.
The shield graphics look absolutely wicked. They have only been showcasing off protoss abilities, and haven't gotten to terran or zerg yet.