The classic Hunchback is really a specialist. It's got the big, short-ranged boomstick pointing forward, so anything that stumbles into its firing arc at reasonably close distances is potentially in for a world of hurt, especially anything in about its own weight class and lower.
On the other hand, it's vulnerable both to long-range attacks (where it can't return fire at all or at least not accurately -- you certainly can shoot at anything within the 7-9 hex bracket, you're just going to fire at +4 right off the bat and had probably better hope not too many other adverse modifiers stack up) and to shots from the rear, where its torso armor is painfully thin and it can only return fire with a single medium laser at best. And its 4/6 movement is at the low end even for 3025-era medium designs -- sure you've got your Centurions and such as well, but you've also got your Griffins and Phoenix Hawks (and Cicadas if you want to go there, even), which pull the average up.
A single Hunchback on its own is honestly not that hard to beat with another single 'Mech, which can probably either outrange or outmaneuver it. It's when both sides field larger forces than that that things get interesting -- sure you could pick at that HBK over there with your LRMs before it can lumber into range, but it probably has the forward armor to stand up to that kind of attention for a while, and wouldn't you rather first take care of that Griffin that's already shooting at you right now?
