Fan of TA and SC was the (suposed) spiritual succesor so to speak of TA. I liked the orginal (SC) but it was a micro manageing nightmare instead of the tactical battle it was advertised as. Huge amount of units, nice screen scrolling and zooming. Bland units (pretty much perfect mirrors on each side) with the expermental Units being the "cool" factor, but they are not used till later in game.
SC2 is a whole different animal. Maps with many choke points, no open battlefields like original. More "go this way or lose" maps, no where near as much expermenting with victory strategies. Very linear maps and gameplay. far to much "Build this or lose" gameplay. its still fun, but takes the unit decisions out of your hands and makes you build specific stuff no matter what (yes, the option to do waht you want it still there, but winning that way would be LONG and painfull, simply put, building the way they want you to is the only way to defeat the enemy in a normal amount of time). The Experemntal units show up a bit quicker with the ability to research, but (I'm not done yet) they seem alot weaker then the old ones.
Overall I think SC was a better game for the sandboxers, SC2 is more structured and follows the more traditional RTS formula.
$10 was a good deal IMHO still.