If it's even remotely close to the original starcraft like your saying, which i'm glad to hear, we know it's going to be a major success and will likely be played for many years. Although, I'm more of a fighting game player and the amount of micromanagement in strategy game turns me off (an example is my heros in Warcraft III seem to die the moment it enters the battle). This is one game I've been waiting for since forever.
They actually pulled off the same "feel" as the original starcraft, however, they made quite a few balance changes that were minor tweaks but have made a huge impact on the game.
For instance, there's virtually no AOE anymore, so instead of like yeur entire army EXPLODING INSTANTLY, battles tend to last alot longer now, and units that had been especially squishy at one time, are not not that bad... such as marines... which since they have to be targeted one at a time now, instead of mass aoe nuked, they are FAR stronger than they ever were in SC1.
Another example, is that almost every unit in the game now has multiple hit attacks for weaker damage, this is an indirect change which has a large impact, since it makes armour far more powerful than previously. A battlecruiser, for example, does 10 damage vs ground units, and 8 vs air, but shoots about 4x faster than it used to. This means, against a lightly armoured ground unit, it does significantly more damage than the old 25+3/upgrade, but against a heavily armoured enemy, it does significantly less, making weapon upgrades and armour upgrades far, far more noticible.
The ability to leap up walls for some units that aren't directly air units is another large change, and unfortunately, screws up gameplay far too much. Reapers have far more power than they should really have for their cost, and can be obtained far too quickly. With terrans able to easily block off their entrance with supply depots early on (which now can be dropped into the ground on command and walked over, making it so they can actually LEAVE their base once walled off, but yeu still can't get in), yeu don't know if they'll make reapers or not, but have to assume they'll have them, which means very irritating forced build orders when fighting terrans, because yeu HAVE to prepare for a reaper rush, or yeu WILL loose. There's no option about it; if yeu don't prepare and they hit yeu with reapers, it's game over, which cripples the build orders of everyone in the game, which's stupid.
Zerg have nil for anti-air until tier 2, since they changed how early yeu can get hydralisks, which's a pain, because a fast air rush can slaughter zerg incredibly easily, unless they devote a large number of resources to rapidly teching (no early expansion for zerg cripples them more than anyone else), or to anti air defense buildings, which also cripples their economy early on.
There's a multitude of other balance issues that are not likely to be resolved before release. As such, the game does not appear to be much past the original starcraft, there's too many vastly gaping holes and far too strict build orders to survive 'cheap' tactics, which require very specific build order counters. With scouting being so much less than it used to be, it's not realistic to easily do this in time to prevent such anymore.
Most counter units don't counter as well as they should for the cost, and virtually every higher end unit counts as armoured, which means they take bonus damage from virtually everything.
Oh, and that's another thing, the old armour system was small/med/large units (1 space in a shuttle, 2 spaces, 4 spaces was the easy way to tell whot a unit had; all air counted as large, except mutas which were small); weapon types were normal/concussive/explosive. Concussive did 100% to small, 50% to medium, 25% to large. Explosive did 100% to large, 75% to medium, 50% to small. Everything did 100% to shields.
The new armour system is a VERY nice upgrade on the old one... units have several modifiers built into them (an ultralisk for example has Bio, ground, supermassive, armoured), and certain abilities can only target certain types (like WC3). The biggest difference, is that all weapons do 100% damage to all armour types, but if yeu're fighting an enemy that has an armour type yeur weapon is specialized against (for example, marauders do 10 damage but an additional +10 vs armoured units), then yeu get bonus damage on top of that. This makes counter units far more effective... or at least... that's the theory.
Problem is, virtually everything has bonus damage vs armoured units, and virtually all the units in the game are armoured, including all buildings. This means buildings die far faster than they should to units that shouldn't be strong against them, and it also means that most of the counters flop hard... for example, a Colossus (new protoss unit) should just SHRED tier 1 ground units, as it's specifically designed to rip through them... except most Tier 1 armies have significant bonus damage vs armoured...w hich a colossus is... armoured. Of course. Soooo the poor colossi get torn apart by the very thing they're supposed to be adept at killing.
The armour system has incredible potential to balance the game far more than the old SC could ever dream of being. The problem is, it has far far far FAR too few armour types and weapon bonuses... and "armoured" is flat out overused on EVERYTHING, which defeats the whole purpose of the armour system in the first place.
As such, around the time the first expansion hits, they should fix this issue by adding more armour and weapon type bonuses, or using the ones they have more diversely, which will allow them to balance the game very nicely.
At the moment, however, they're barely making use of the armour system at all, and when they do, it's very poorly utilized, or abused.
The game has all the tools needed to BECOME ridiculously well balanced, they have so many more accurate options on how to tweak and adjust balance than before that it's not funny.
They just aren't using it properly yet is all.
So, as I said, the game has very obvious glaring flaws in balance right now. Give it an expansion, and that should fix most of the issues with it. The second expansion should refine it to well beyond that of brood wars, and make it probably the #1 RTS game for another whole decade.
But right now it's not even on par with brood wars. I'd suggest picking up a copy of supreme commander for now (the first one, not the second). Far better investment until SC2's expansions are released, which could take awhile.
Keep in mind, all of this is being said by a massive blizzard fangirl... I just am not going to pretend that the game is something it really isn't XD