I think it is important to stress the importance of the continuous resource model a little more. In Blizzard-style RTSes (Warcraft, Starcraft, etc), when you purchase something it spends all of the money at once, then churns away until that thing is done. In Westwood-style games (Command & Conquer, etc) the money is spent as the thing is building. This also allows building times to be directly proportional to the cost.
TA is closer to the Westwood style, as building times are proportional to the cost. But it's also more like the Blizzard style (specifically Warcraft II) in that buildings are built with construction units, and the more units you have, the faster it builds. In a twist, the construction units can also speed the building of other units.
The practical upshot of all this is that the resource model is far more dynamic than most other RTSes. Things which effect your resource production happen now and in real time. The rate at which you gather resources is far more important than the actual amount of money you have. When your resource collection is destroyed, you can't spend much before you're out of money. "Strip-mining" strategies of other RTSes are rather pointless in TA, or at least would be done for completely different reasons.
On a completely different note, TA also boasts a phenomenal soundtrack by Jeremy Soule, who composed music for such other games as Secret of Evermore, Icewind Dale, and the upcoming Unreal 2. It is orchestral music, of a very grand scale. The tracks are divided into various categories, like building, battle, and defend, and the game will play from the appropriate category depending on what is happening in the game. If you have this game, put the CD in your CD player right now and listen to track 6.