2 words people!
Anyway. The E-25 in its current form will be a tier 7 premium tank destroyer. It will cost about 3k gold aaand its natural competitor will be the SU 122-44. But can the German steel stand up to the russian totally not OP tier 7 TD? The answer is...It has a decent chance actually.
The E-25 is at mere 26 tons, carrying a 700 horsepowers engine. That gives it 25 hp/ton, more than enough to use its top speed of 65 kmph(20 reverse) Hello Hellcat 2.0! Tracks traverse at 42 degrees so its going to be speedy enough alright Its hard to say yet, but afaik - its going to be like a shorter Jagpanzer IV, so you are in luck - good camo rating, and being a hard target at distance will be 2 of its perks. Taking forward positions fast, won't be a problem. Just make sure you don't get shot because...
Armour wise - the E-25 is again like a shorter Jagdpanzer or rather, a bigger Hetzer, except a tier higher... so basically - everything you meet will penetrate you frontally. The gun shield might bounce a shot on a lucky day but thats it. with 830 health you can't afford to tank shots either. The 25 tons become a problem in this area too - don't get rammed.
And now the juicy part - the gun. -8 +15 degrees depression. Allmost 19 RoF, 0.31 accuracy, 1.5 aim time...198mm penetration with AP rounds....and its a 75mm so ammo will be cheap. Sold already? Wait there is more - view range is 360 meters, bonuses and equipment not included - that means a binox can make you your own scout if need be, especially when we mention the size and speed. Basically the only bad thing about the gun right now is the ammo capacity - 60 rounds, that will run out in no time, and (perhaps) the gun horizontal traverse, which we don't know yet.
Will it be good? Yeah - you get a fast, nimble, probably stealthy machinegun sniper. A Panther with a TD's camo rating and freakish RoF. The good penetration and accuracy will likely even out the alpha damage of the Su 122-44, because you won't have to use gold shells often(if at all) and you will rarely miss a shot.