It's time to put some perspectives. First of all, since i won't dive into the gamefiles, this is just info collected from the differents stats sites which may or may not be updated, experience and memory.
-It's accelerates/decaccelerates faster
-It's hull/turret mg has higher DPS to account for the lack of gunner upgrade. The DPS is basically the same as a Tiger with a gunner.
-Increased sight (specially with bulletins)
-TWP working as Stugs TWP meaning that it doesn't target ground.
-I'm not sure but does it have 160+ hp ?
http://www.coh2-stats.com/vehicles/tiger_ace_sdkfz_181_mp
-25% less MP and 90% less fuel for as long as the TA is alive or 10 mins*
*Someone corroborate this plz.
TA cost: 800mp + 75mp*min + 90% of your fuel income. It hurts if you have map control, it doesn't if you don't have it or if you don't actually have fuel (P4 all day everyday).
On a 50/50 situation, it would have cost you 180-200f.
Why the TA is good:
-You don't have map/fuel control? Don't worry save mp.
-P4 heavy into TA. The moment you call it, you are 260f + 200mp ahead of your opponent (Tank is valued more or less as 1000mp 260f). If you trade inmediatly for example with an IS2 you are ahead.
-Trade P4 1v1 with T34s/Sherman/Jackson and then call TA.
-Use it when the game is ending since there is no drawback when the game won't last 10 more mins.
-CPs after 7-10 are obtained pretty quickly since combat scales pretty fast. 4 more CP than a normal Tiger is not as much. And still, you don't neccesarily want to get it inmediatly.
TL;DR: the unit is "fine", how you get it's not. On 2v2 is bearable since you can focus fire it with your parnter and on higher modes you have plenty of support and resources (fuel) don't matter as much.