I'm no Warmachine expert, and in fact have only played a single game of Mk. III. That being said, I try to keep up with at least the general trends on the forums.
As a whole Cygnar is a good faction in Mk. III. Some would say overpowered, but no one can point to anything that is completely over-the-top. They are just solid.
The Stormwall was a key piece in Mk. II. In Mk. III, things are better balanced, and so it isn't nearly as essential a piece. It is still a solid choice, but there are good lists both with and without it.
The Storm Strider, sadly, doesn't work well. I absolutely adore the model, but it doesn't do a good job on the table. It is anti-infantry, in a game that has moved more toward warjacks, in a faction that already has plenty of anti-infantry tech. I'm sure I'll still play it just because I like the looks, but it is in no way "competitive" at the moment.
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