LL might be a bit too strong now, and I think some of the balance changes may have smoothed out tonnage performance a bit too much, but overall it's a vast improvement and there's much more choice in how to build your mech.
Nope, LL are still crap compared to the good weapons. Damage per adjusted ton (meaning weapon+1 ton ammo+heatsinks to dissipate), LL are only a 3.6 damage. Mediums are 5, SRM6 are 6, LRM15 are 4.6, LRM20 are 4.7. AC10 is now a 3.8, and AC5 is 3.75. Now grant it the AC10 and AC5 have only 1 ton of ammo in that calculation, and will have limited number of shots (on the same note, how many matches really need more than 15 rounds, and in the case of the AC10, with 2 tons of ammo, it is still approximately even in terms of damage at 3.6, while at the same time doing more burst damage to a single location, with the same ranges as the LL, and the AC5 has better range than the LL). PPCs are still useless until they cut another 14 more heat (which would get them in the 3.5 damage per ton if they did, but that is still crap, for it to be really viable it needs to at least compete closely with the AC5).
Only thing that really changed is that you now have a viable choice between using LRMs and SRMs depending on the Mech.
On a side note, I gave up trying to get heavier mechs before the mission. With the recent changes in heat for LRMs, I was able to convert the thunderbolts I had (and was not using) into a viable missile platform with a LRM20+LRM15 and 5 tons of missiles. The last missions were a little tough (if I played it again now knowing what would happen, I would most certainly do better). I got 2 mechs roughed up a little more than I would have liked (luckily one was a battlemaster which was there mainly to absorb damage in the first place, but had some real good short range punch). Wound up having a leg, arm, and side torso (on the same as the arm) down pretty deep in structure, but didn't lose any weapons or modules. My black knight got beat up (1 leg had litterally 1 structure left about 2/3rds into mission, and had head and CT in structure). In the final battle I made a costly gambit which resulted in my Highlander losing his left torso and arm (better than the right side with the gauss rifle, but still lost a double heatsink which was un-replaceable), but that was the only real damage from that battle (and it was the last in the campaign, so...). So in the first of the two battles, I use a Battlemaster, Black Knight, Thunderbolt, and Highlander, and the final battle, the Atlas, Highlander, and 2 Thunderbolts (which simply wrecked, as I used jump jets to get them up high on the wall and rain down hell with the height advantage, either splitting fire on two enemies each (where-in each thunderbolt attacked 2 different enemies for the breach shot advantage), or focusing fire on a single target which was not braced, utterly devastating it).
I toyed a bit with the Battlemaster, swapping out a medium laser and a heatsink to add 2 machine guns and a ton of ammo. I believe I liked it, as it was always a brawler due to its speed. While 2 small lasers would have provided more damage, the upping of medium lasers heat forced me to make a change to cut back on overall heat, but the critical damage that the machine guns do (as well as 5x higher chance for head damage) made them the obvious choice. I also had a grasshopper I picked up at some point, which I setup with 5 medium lasers and 4 small lasers (again, due to its speed, it made for a good brawler, and that greatly increased its damage at close range while cutting down on temptation to use more weapons at long range when it couldn't dissipate all the heat).