Good news is 1.1 is already in the downloads. :)
The added 'game options' will allow you to have up to 4 bullets at a time in both vertical and forward guns (which makes things a lot easier to shoot - especially when there are a constant stream of bullets), you can also give the aliens a longer wait before they appear one after the other (setting it to 5) so you get more time to shoot each one before they pour onto the screen and start dumping bombs down.
I think I also adjusted the bombing frequency to be slightly less at the start, but off the top of my head I can't recall.
The other options are more small 'features' - one switches off the ability to move while in the air if you want to make it a tad harder. The Jump length can be tweaked to allow jumps to be longer or shorter (2 is the default) - though that can also lead to slightly harder game play as well.