Personally, I prefer the gritty look to the original Starcraft. The new Crucio Siege Tank is not so much of a hard-on as the Arclite, reason being for its cannon and deployable supports. But I'm just nitpicking. If Starcraft II wanted to make its game look better, I say they did a good job.
The Arclite seige tank boasts 70 damage AOE per shot while the crucio only offers, what, 35? Three Arclite seige tanks manned properly can probably tear down a Thor, not to mention that the siege tank requires less teching.