So, I just finished MW5:Clans' Ghost Bear DLC, Flash Storm. I have thoughts.
The DLC is fun, and I enjoyed playing it. But, it's too short. I don't mean that the pilots won't achieve maxxed skills though the campaign (they won't,) but I presume that's done to make choices meaningful. No, the reason I feel the campaign is too short is that you simply do not get the chance to use all the 'mechs available to you. This is the main problem I had, playing through the DLC on Expert difficulty.
The way that the game paces your tonnage requirements makes it very difficult to use 'mechs like the FireMoth, Hunchback IIC, or even the newly-introduced Night Gyr in missions - because very quickly you enter the fight massively under-tonned for your mission allotment. I had missions where I was short an entire Heavy 'Mech's worth of tonnage, and my battle damage assessments at the end of the mission reflected that. For most of the campaign I was chasing tonnage allotments and trying to fill out my 'mech roster, - I'd much rather fill out smaller tonnage allotments with a wider variety of 'mechs, and making use of my pilots' 'mech affinities.
There are some other issues I had; but those were relatively minor. The research system should give you a warning if you start a drop without anything actually being researched. Some 'mechs' architecture is such that they take an ungodly proportion of their damage to the Center Torso, drastically reducing their effective durability, but the main impediment to my enjoyment of the missions was the way the game penalized me for using all the neat toys I was offered with the DLC. I realize that I can start a New Game+ and use more of those toys in the earlier missions... but it feels clunky to rehash events I've already played in order to use those nifty 'mechs.
That being said, I'm still up for more DLC, here and in MW5: Mercenaries - I love fighting the Adjective Animals more than I enjoy powering their fascist war machine, after all. XD. One thing I'd like to see in both offerings is better Star- and Lance-mate controls. I would really like to be able to just park some pilots in fire support positions and then order all of my direct-combat builds to focus fire with one keyboard command - instead of having to pause and use the battle map to do. that.