I haven't had the pleasure of trying out all aspects of this DLC, but so far, I feel I'm being punished for buying it.
The infiltration missions stand out as some of the worst, as it's impossible to "sneak" with even a 20t mech. And it is extremely time consuming having to watch your step all the time.
Problem is, your mission targets are at the very location guarded by at least one mech that WILL detect you - most of the time.
Leaving your AI lancemates, so they don't wreck every area you're trying to stay hidden in, does not work either. I mean, they do not "follow". They walk in front, or directly beside you most of the time, crushing anything underfoot! (BTW: The AI lancemates seem to be invisble to the enemy until combat)
Only option is to close in on in a suitable spot until your're detected, then commit to combat.
This does not work well with a 20t mech. At all. Especially considering the 'mechs waiting to pounce on you. Also, when detected, all relevant guns are already pointed at you. So the first shot is theirs, if there's more than a single enemy watching. For the most part, there is.
I have done many, many, restarts of the missions to try finding the right approach. Mostly I load a game from before taking on the mission and take another path all together.
I've spent hours on a single map only to end up failing. HOURS! And by that time, I am not very happy.
No reward is worth this kind of work. And work it is. Truly.
As for new maps. Having the entire entourage getting stuck at certain places doesn't bother me too much, for I usually manage just fine on my own anyway. Still, it's an annoyance factor.