I enjoyed it quite a lot, after playing for 3-4 hours. I think the basic rifle class is quite weak. I didn't experience the snipers, but after playing the grenadiers and the LMG, the rifle felt like a real let-down, for a class that should be the bulk of the force. I think in general the guns are a bit unresponsive with the new system, but it feels the worst with rifles. I'm not sure what would make them more interesting, really. Perhaps what it really comes down to is play style (riflemen aren't great in public when there's no organization).
I loved the LMG class, it's interesting how you can seem to get better accuracy from crouching, and are otherwise firing from the hip quite wildly.
I had a lot of problems clicking through weapons with the various classes (French grenadier has a few options, and the arrow buttons beside them never seem to correspond with the correct weapon; ie. I click to change grenade and it changes pistol).
I didn't play a lot with the artillery but the mortars seem like a really nice touch (I tried them only once and wasn't sure how to aim it, switched to something easier). I didn't try HMG either because it didn't seem intuitive, but I might be more adventurous next time.
Overall I was quite impressed and I had a great time, thanks for all the work folks! The maps, uniforms, and weapons are all really beautiful and bring WW1 to life in a very real way. Most of the maps also seem really well-designed for the gameplay, as well.