I'm just going to list some stuff that popped out to me on a mock-up.
1) The boxes. I'm liking the availability of everything immediate, but if you're going to go with asymmetric design, do more than gray boxes. Add shapes, break those shapes, basically anything other than an excel cell filled with color, I'd say.
2) Release notes are an immediate concern (and good on you for providing them easily), but having an easier access to your website (preferably a landing page with access to bug reports and general forums, ESPECIALLY in the beta) is preferable to me. Plus it can balance the asymmetry of the menu buttons.
3) Don't be afraid of a big title! The ship marking is a bit too subtle, and there's nothing wrong with reinforcing your game's name. People are going to use screenshots of your main menu, and nothing wrong with a big title drop in there. Unless, t's outshadowed by...
4) The BLOOOOOM. I play warframe as well and it's as bad as this'un. Unnecessary glow takes away from the focal point, in this case the lovely ship. By all means show us that the engines are powerful, but not with a glare that overpowers your game's name and your company logo. Front glow is even worse.
5) Adding more dynamism to the background in the form of missiles, lasers or other types of projectiles from a presumably enemy unit might give you more action without compromising the strength of the main menu. Adding a bit more to the flight loop animation (really shallow angle banks and whatnot) might also help, otherwise it's just a 2d object bobbing up and down.
And for the future, whenever you're in doubt of a visual design, I'd suggest squinting and looking at it. Here,
have another mock-up. Ze bloom, it's killing everything! Apart from that, none of the buttons are popping out! I'll make yet another mock-up to show what I mean by popping up and asymmetry.
fake edit: okay, bloom is getting lowered, hooray!
real edit: here have the button mock-up:
Obviously a bad mock-up, but that's what I mean by breaking the shape a bit. Placing more emphasis with just added color is also a possibility for promoting the tutorial over other options. Or hell, just make it the biggest button in there on first-run.
Simple contours, text color, border color etc can add a lot more to boring bland clicky boxes. I'm going to suggest you guys to have the player pick a color upon account creation and use that color to add accents to text boxes.