Few suggestions

[CallMeGanymede]

I would really like to see a little more variance in weapon types.

For example, perhaps a flamethrower, or stream of electrical energy (that arcs to a nearby enemy maybe)... something like that.

Or a shield as an alternative to a melee weapon (and you can wield a pistol while using the shield) or something.

Also, if possible, maybe a benefit for maxing out a frame's capabilities? Like the ability to use one of the abilities (the first ability presumably) while within another warframe. (For example, maxing out the Volt warframe gives you access to the Electrical Blast ability, which could be switched out with a second warframe's first ability.) I don't know, just something to make things a little more interesting in terms of customization.

Love the game, can't wait to see where it goes from here!

[Mibu]

More weapons I assume are coming. Different types? maybe?

Swapping of abilities? No thx. Additional trees for varying abilities? Maybe.... just maybe... 'cause right now it's just 4 abilities and no variation or a freedom of choice here.

[McGuffin]

Actually I would love to see each ability get its own little tree. Whenever you level up and select the appropriate ability, instead of it automatically improving, perhaps you could get a point to spend into the tree of that ability instead. Then you can choose what aspect of it you want to upgrade such as speed, power, range, damage, etc etc.