In short, the T-54 First Prototype is effectively a T-44 with increased armor and hit points at the expense of mobility and speed, or a Type 59 with reduced turret armor and penetration, increased upper hull plate and gun soft stats, and full matchmaking.
It makes up for its lack of speed and penetration with thick frontal armor, allowing it to effectively nullify many guns with less than 175mm of penetration, making this tank extremely dangerous at top tier. The upper hull plate thickness is 120mm, but the angling gives it an effective thickness of over 200mm at its weakest point, while the lower frontal plate of the same thickness gives around 160mm of effective thickness. With even a slight angling, the upper plate’s effective thickness increases to 240mm, while the lower plate can reach 183mm, making it impossible to penetrate without the use of gold rounds for many Soviet vehicles using the 122mm guns, and nearly all tier 6 vehicles. The only actual weak spot is the turret, with the mantlet having 180mm of thickness with no armor behind it, a low-profile cupola located at the left side of the turret, and the roof, which is only 15mm thick, and can be shot at a downward angle from taller tanks such as the Tiger II, M6, and KV-5. Needless to say, its armor is virtually useless against most tier 9 and 10 vehicles that it faces on a regular basis, so a less aggressive play style is advised as a bottom-tier.
Despite its great armor, the offensive capabilities of this tank are limited; Having only 175mm of penetration on its AP shells makes it almost impossible to penetrate higher tier opponents frontally, and even sometimes struggling against the side armors of some vehicles. Thankfully, its Damage Per Minute is slightly above average, and its APCR shell has a decent penetration of 235mm, which can frontally penetrate most weak spots and side armor. Additionally, its premium vehicle status can help offset the credit cost of premium shells. It should be noted that this tank can only carry a total of 34 shells, so running out of ammunition is a possibility.
The mobility is somewhat below average compared to other tier 8 medium tanks, but hull and turret traverse speeds retain a favorable speed, making it competitive at close-range brawling. While it cannot circle around most heavy tanks without sustaining a few hits, it can easily bring its gun around against light tanks.
While the view range on this tank is relatively poor at 360 meters, its camouflage value is decent, which makes scouting somewhat viable with the use of concealment.
In conclusion, for a relatively cheap premium tank at tier 8, this is an excellent vehicle. In the right hands, this prototype can easily earn large amounts of credits, as long as its strengths and weaknesses are properly understood.