UncannyGarlic

Agreed on all accounts. The best tutorials are the concise ones that are all about teaching the game. I also agree that tutorials that are part of the story/game tend to be worse because they are so much less concise and tend not to be designed in a chapterized fashion for easy revision.

Is the air combat RT or RTwP? Are there different speed options like on the Geoscape? If it's RT with no way to slow down the action then I can understand the complaints.

Either see-through walls or an icon floating on top of the walls is a necessity in my mind. If enemies are visible to my units they need to be clearly visible to me, as the player. Enemies being hidden from the player behind terrain is a problem that a lot of 2D isometric tactics had back in their heyday but that's no excuse as it was annoying then too.

I agree on both counts, though I'd suggest further, more specific breakdowns. I'm pretty sure that most TRPGs have something to this extent, here's an example from Final Fantasy Tactics. Presumably some sort of in-game wiki (an updated version of the UFOpaedia) is planned as well so that could also cover it in text form (Civilization V comes to mind). Just having a preset map for some different general map types would be nice. For example, one for each ship design. That said, I've never had a problem with experimenting in game and reloading so a sandbox is an ultra-low priority for me. It might be a bit annoying to make but a virtual reality/holodeck type sandbox is always a possibility, though I still think that the plywood is the most setting appropriate.

Is there a volley option? If not, that might be a nice addition. I'm not sure how many weapons you plan on having the best fighter being able to equip but if it's more than two an option to link weapons and fire either in unison or volleys could be nice. The volley option could either be with a preset delay or a customizable delay. This is all assuming that currently you have to deactivate a weapon until you get in range then pause, reactivate it, and resume in order to fire in volleys.