- Shields now have infiltration values. They are very bulky and thus take a long time to infiltrate, more than a grenade launcher does.

- Tier 2 and Tier 3 Shields have single-build costs now. The Tier 2 one requires Plated Armor research, as well as 20 Supplies and 3 Alien Alloys per shield. You'll also need 3 Engineers. The Tier 3 one requires Powered Armor research, as well as 40 Supplies, 5 Alien Alloys and 5 Elerium Dust per shield. You'll also need 6 Engineers. These costs/requirements apply to both the humanoid and the SPARK versions of the shields.

- The SPARK and MEC Trooper version of the Shield Bash ability can only be used once per turn, since it does a 2-action stun instead of a disorient. You can get rid of this cooldown entirely (or make it longer) via XComShields.ini (change the value of SPARKSHIELDBASHCOOLDOWN to 0 for no cooldown, or a bigger number for a longer one).

- Shields now come with the Taunt ability, should you want an option to guarantee some aggro.

- En Garde (from Mitzruti's Perk Pack) relies on Taunt to activate instead of Shield Wall.

- Shields can no longer be equipped with Assault Rifles, Shotguns, SMGs or Bullpups. They will only be able to be used with proper single-handed weapons (Swords, Pistols or Sawed-Offs). As of this post, the only LWOTC class (base or mine) that can use Shields with no config changes is the Stormrider. Edit: the Hoplite is released and it works with them too. If you're salty about this change and want to wield those weapons with shields once again, you can go into ModJam's XComShields.ini and comment out the 4 lines starting with
"-AllowedPrimaryWeaponCategoriesWithShield". Edit: As of the Bio Division update, this feature is axed so as to not break the Bio Barrier Troopers. You still need to manually add Shields to classes other than Stormrider and Hoplite, though; Mod Jam does not do that for you.

- While not a "change" persay, you should definitely grab Lago's Shield Rework mod. It makes them far more balanced and unique in how they play, and my own class that uses Shields will be designed with that mod in mind.