So I've been playing because of the Free Weekend and will probably buy the game but I do have some feedback and also complaints that discouraged me from playing.
Training Grounds (what discouraged me from buying)
Whilst veteran players should be allowed to play this game mode, they should not be fighting new players in it. Rank 5s should fight no-one higher and nor should rank 10s. Beyond that though anybody should be allowed in a match. With how different this game is from others new players need a space to learn stuff but can't right now, sure they can use offline mode but I didn't know that existed before being told so (and even then you can't gain XP : / ).
Team Balancing (what also discouraged me from buying)
I've played on multiple teams filled with new players against mainly veterans and it isn't fun. Like before it's not possible to learn the game when you're always dying. This needs to be improved and more well-balanced. A Ranked Match Maker option might also fix this.
PvE Gamemode
Playing Training Grounds against AI was a lot of fun and I would like to see this expanded upon personally. A game mode without PvP but instead PvE up to 4-8 players I think could be great fun. Maybe wave defence or similar to what we have now.
Training Area
An area to test out weapons and combos on dummies and pieces of wood would be fantastic. Not much really to say here.
Short Little Videos Showing How Weapons Work Or Just In Combat
Similar to Red Alert 3 or Just Cause 3/4's weapon videos, it would just be showing the weapon in action or if it were done like Red Alert 3 a short little explanation of how it works.
Customization
I have to say I love the customization but it would be nice to see Gambesons and more Kettle Helmets. The options for helmets for the Masons are also a bit unappealing imho, though that's just my opinion and I'm sure many like them.