I PM'd Seriyu with my part of the Bay12 feedback email. I'm pasting it in full below if anyone else is interested:
**Combat**
Combat itself (barring the brick-wall scaling issues to be addressed in the upcoming overhaul) feels dynamic even in its bare-bones form. The system feels like it has lots of potential, but these issues stand out:
-Hunting bows are pitifully weak even compared to the relatively weak ranged weapons that may or may not be available, based on luck. I'd prefer they be an alternative to (buffed up) guns of the same tier, with the tradeoff being zero pixels as loot on a hunting kill.
-Some melee weapon arcs are too narrow. Spears only feel viable on flat ground, which is rare enough to make me not want to use them at all. One-handers feel fine to me, because the shield makes up for a tiny arc by letting you soak damage to position yourself, but as it stands, between the 2H axes or swords I've found, spears just don't pass muster. They would be infinitely more useful if they stabbed in small arc aimed by the cursor, something like 45 degrees, so they could hit targets below you that axes might miss.
-Knockback seems very excessive, both on player and monster hits. Some enemies knock me back for a full screen, which is disorienting and breaks the flow of fights. Conversely, I can keep two or three overlevel critters at bay with an assault rifle, which makes some ground combat attacks irrelevant. That would be fine for big, powerful weapons, but machine pistols or assault rifles would feel better if they had at best a stagger or flinch effect. This would also make the different ranged weapons feel more distinct.
-The enemy health and attack display is hard to follow in combat, and takes my eyes off the fight. A floating health bar above wounded enemies would remedy most of my complaints, but the attack list per critter is also difficult to read if there's more than one monster attacking you at the same time. I'd like some way to keep track of all the critters I've seen on the planet I'm currently orbiting, with the list being wiped when I leave orbit. Alternatively, once pets are in I would like to save the general attacks and a view of critters on certain planets into a database with planet coordinates in case I want to return for pets later.
**Exploration**
-As above, I'd like a simple in-game log system (perhaps accessible from the computer in front of the pilot's chair?) to let me take notes and coordinates of interesting planets with cool stuff on them. Sometimes I've been slightly too low to comfortable survive a planet, so I had to tab out and copy the coords in notepad. In-game would be much more convenient.
-The flashlight isn't that useful at all. Underground I place torches constantly, and above I just don't bother exploring at night. I'm sorely missing Terraria's shift key (it would bring up the appropriate lighting source on the cursor when held, either a torch or glowstick or flare gun). Also, making torches drop instantly in water is a little obnoxious, they should just fail to be placed without dropping them in the water. Later tiers might want a flare gun similar to Terraria's for quick and dirty temporary lighting in a larger area, like caverns.
-It's been mentioned that there's little reason to go spelunking when you can mine surface ores and the like. I believe there's a lower-depth rebalance coming, which I approve of. On that, lower depth should have tougher monsters with better loot in chests, and while there are now larger deposits of ore near the bottom, I didn't notice the size of gold clusters growing much, if at all. Perhaps there could be a smoother difficulty transition if the planets across a difficulty tier had ore availabilities more distributed (easy planets have some to moderate copper, mediums have decent to lots of copper and some to moderate iron, a little gold, hard planets have abundant copper, decent iron, moderate amounts of gold near the bottom. Next tier could start out with all 3 in abundance and phase out copper for more gold, etc.)
**Progression**
-Sandbox mode: I propose an alternate mode for people who don't particularly enjoy the combat progression or bossfight unlocks. Sandbox mode would start with every sector unlocked (but still in sector 1 with starter gear) and just let people progress through the game as they wish, exploring planets in their comfort zone at their leisure. Alternative methods for crafting the boss drops would be needed, and I don't think this should mix with regular adventure mode characters, but a truly open universe style of game would be nice to play with on other characters if I get sick of the boss fights later.