OK that's good to hear.
Can you give me the name of it so I can look it up to satisfy my own curiosity? I don't have the time or skill to really get involved in TF2 but I am interested in hearing about it.
The Heavy's spin-up and spin-down time on his minigun, as well as his movement speed while spun up. They buffed it by half a second, while also giving him the items the GRU, (Gloves of Running Urgently, which hurts you -3HP every second while buffing your movement speed to near base speed), and the Sandvich (which can be eaten during a taunt for full health, thrown on the ground and picked up like a health pack to heal yourself or your medic or other teammate for 150HP), and Tomislav (which has a silent spinup and even lesser spin-up time in return for a 20% lower rate of fire).
Together, these (the Tomislav eventually got nerfed, and is currently nerfed in the beta for -50HP) formed the core Heavy loadout, and became the bane of pub servers. A Heavy with a Medic could now sprint to the front line for no health cost, easily engage and disengage from enemies, and heal himself or his Medic on command, thus negating huge parts of the downside to playing Heavy (slow, takes time to spin up, draws fire so difficult to attack without a Medic).
They've done some nerfing though: today they made it so the Heavy can't be healed by throwing their own Sandvich and picking it up; that will just regenerate their Sandvich meter. (A lot of Heavies would throw a Sandvich before fighting, then simply back up onto it once they started getting hurt for an instant 150HP boost).
On a good/skilled server, Heavies of poor or middling can be easily negated. Once the Heavy knows what he's doing, however (or is playing on a casual server filled with unskilled players), it becomes an imbalanced proposition of effort vs. reward: the Heavy puts in little effort, is greatly rewarded, anyone who wants to take out the Heavy has to put in a disproportionate amount of effort to kill him compared to other classes.
It's not game-ruining, but it's an annoyance.