The concept is actually fairly nice. I mean, games like this are addicting -- but, and there's it, there's not enough variation to keep coming back to it. It's something you play once, do a time or two, and forget about for a while. There's no real lasting appeal.
I'm going to make a couple of points and I hope you can do something with them. Whether it's for this game or later games.
1) The game looks really bad from a graphical point of view. I'm talking about your menu screen here, the game itself is too simple to complain about in terms of graphics. The text-buttons look cheap, the background has nothing to do with anything, the "created by"'s dark colors are too much of a contrast with the pale blue-greenish shades of your background and title. The title itself is a bit plain, and it doesn't fit well on the background. I'm not saying that you should spend hours on creating one, but spend a little more time on it... look up a tutorial for making one, get help, something like that.
2) There's a "level-up" text once in a while, but it doesn't seem to change anything. The powers remain the same, and if the speed goes up, it isn't really noticeable. If you want to work with a level up kind of thing, then change things around. Less power-ups, other power-ups, "bad" bubbles, faster bubbles, moving (not just vertically) bubbles... things like that.
3) Speaking about power-ups... They make the game too easy. I barely had to press normal bubbles myself; I just had to press the countless of red, yellow, and "up" bubbles and voila: done. I didn't feel accomplished at the end, just cheap. There are just too many of them. Sometimes there were 5-10 seconds that I had to do absolutely nothing because the game was making combos for me. This isn't bad, but it happened too frequently.
4) Some music would be good. Sound effects are great, but being able to have some options would be better.
5) It's a game about archieving the highest score, but there's no indicator whatsoever on how well I did. An in-game scoreboard would be fun. A recent example is Retro/Grade: it shows which place you have on the board and your score. Having some kind of goal would make this more fun.
That's all I can think about at the moment. Like I said, I really hope this can help you. Good luck for any of your further projects!~