To echo others, the 3025-era Grasshopper is just a beast. It's one of the finest heavy Mechs of its era and worth every C-bill it costs you. It's mobile, has a nasty bite, no ammo concerns for its main weaponry (so it can operate away from supply lines for long periods), has hands in case you need them, and is surprisingly tough to kill.
However... the 3050 'upgrade' was a criminal act against a previously-dominant machine, and while later Grasshoppers were definitely better than that lemon the line has never really recovered its role on the battlefield. Part of it is that its uniqueness is gone- in its day, it was one of only a small handful of jumping heavies, and today it's easy to find such machines. It's not particularly fast in-general either- 4/6/4 is fine for 3025 play, but by the end of the Clan invasion fast heavies at 5/8 were becoming increasingly common. It's not hard to find 5/8/5 even, such as the Thanatos or the excellent Falconer. Grasshoppers tend to not use things like XL engines and such, and while that makes them tougher to kill it also means they pale against newer machines that use those tricks.
That's not to say a Grasshopper in the Jihad era or beyond is a waste of time, naturally. In fact, with the drawdown of Mech armies post-Jihad, the Grasshopper regains some swagger! On battlefields where a Mech may be a fairly rare sight, particularly a large one, the mobile and unpredictable Grasshopper becomes what it used to be again- the centerpiece of a mobile army, lashing out again and again with laser fire and a handful of missiles while leaping between cover positions. Simple upgrades to the 3025 model can make it quite happy in a 3145 army (a 3050 GHR is best stripped and totally refitted), and the newer versions with the torso-mounted cockpit and head-mounted electronics suites are even handier on battlefields full of infantry and the like.
Short version, Grasshoppers are absolutely dominant in pre-Clan and post-Jihad battlefields, struggle in the periods in-between, and are almost always worth keeping on-hand if you end up with one in your possession- they're great fun in most roles.