I'm writing this after buying the tank, so I know firsthand how it performs in the field, though only from a small sample of battles so far.
So, here we go
Firepower – in raw terms, it is good. This gun is more or less the same as the long 107mm used on the KV-4 heavy tank – alpha is the same at 320, and penetration is very similar if not identical on both standard and premium rounds (iirc, I have not played the KV-4 in forever). Unfortunately, for a medium tank the hidden dispersion values are extremely poor, and the aimtime is likewise bad. Even running with bounty stabilizer and BiA, the gun tends to misbehave a lot, and fully aiming each shot is pretty much mandatory unless one wants to rely exclusively on RNG. Gun depression is bog standard for a Russian tank at -6 degrees.
Mobility – oh boy, this is painful. On paper, the tank can achieve a top speed of 58 km/h with a fairly respectable 17plus hp/t. Cool yes? Well, no. On paved ground, the maximum cruising speed caps at about 45 km/h, whereas on softer ground it drops to 40 km/h. It is possible to achieve the listed top speed only when accelerating down slopes (e.g. Himmelsdorf hill). Hull traverse is fairly quick, but turret traverse feels somewhat sluggish for a Russian medium.
Survivability – here I am reminded of a character from the PS2 port of Quake III Arena, described as "crunchy outside, soft inside". The Object 274a has a pretty good armor profile, the turret is very solid (beware of the weakspot above the gun barrel though), and the upper glacis can achieve autobounce with little effort. The problem begins when shells start cracking the armor, because even with improved hardening the tank will cap at 1300 hitpoints maximum, and with so many Tier 8 tanks having 440+ alpha these days (plus the ever present artillery hitting for 500+), it really is not hard to empty that healthpool quickly. Long story short, it is extremely hard to make successful risky plays in this tank. It does have good camouflage though, so having a crew trained in that can help (with only paintjob, stationary camo is about 19,2%).
Profitability – adding this because as a premium tank, one good reason to buy it or not would also be if it makes good credits or not. IMHO, Object 274a is a poor credit maker. The tank's repair bill is very low (fully destroyed we are looking at about 7.7k credits, unless the destruction came from an ammo rack in which case the cost will be higher), but each standard shell costs 1010 credits, so for the damage they do they are very expensive. Premium shells are however fairly cheap, at 4k per shot. I wonder why…
In conclusion, this is a very standard, un-broken and un-OP tank that, in the past, would've been sold in the classic format of standard/ultimate/supreme and no one would've so much as raised an eyebrow at it. It is reasonably good without being overpowered, and has some nice strengths kept in check by crippling weaknesses.
Do I think this tank is worth grinding or paying for?
RagingRaptor said in his review – if you have the CS-52 LIS, you can easily skip Object 274a. I will go further and say, this tank is definitely not worth a marathon regardless of which premiums you already own, and WG only shows their greed and disrespect for the community by locking it behind such a paywall.
If you are yet undecided, I urge you to keep your money and sanity, and ignore the Polar Challenge altogether. I'm sure there will be better opportunities in the future (or hey, if you want a Russian Tier 8 premium, just wait for T-44-100 or buy T-54 Proto, both are still more than adequate for the current meta).
Hope this will be of use.
