Pretty good
Not bad. I think there are a few balance issues, but overall not a bad TD game.
Things to consider where balance is concerned:
In the mid levels (haven't gotten to the highest yet), the worm enemy seems way overpowered. Compared to the boss, a column of worms has many times more hitpoints(and I think is slightly faster). Often times, a defense set that will easily take care of every other enemy before the halfway mark will only be able to kill one or two high level worms. Something to consider.
Might want to take a look at high level dragonflies armor vs their speed. Not saying it necessarily needs improvement, but it's something to look at.
The "boss" needs work. For one, it's the same every level, just higher HP. It would be great if it changed from level to level or area to area. Also, considering the strength of some of the columns of invaders that come through, the boss is gravy. Rarely has he made it past my first couple of gadgets before he is decimated - this of course is owed to his laroriously slow movement rate.
Other general thoughts: More variety for towers would be nice. I personally never use gnome laser/net. Seems that the drawback of either land or air is way too much of a hurtle to the two, so I always go with rockets (Laser has a pretty slow fire rate, considering you say something like "automatic" laser in the description)
I can't personally see any reason to use a rose. The cactus is faster, more powerful, can be upgraded to be much better, and isn't all that much more expensive. I don't think the range helped all that much.
Again, maybe a few different types of towers and a few balance tweaks, and it would be great.
I wouldn't mind being able to see the range of a tower that I've placed after I click on it.
Some GOOD things, lest you think I'm complaining:
Very nicely done graphics, I love the cartoony, relaxed atmosphere of the game. Very groovy. Also, very addictive. It's just challenging enough to keep you engaged without making you over tense.
The interface is very smooth, very professional. I've bought commercial games with crappier interfaces than this. Simplicity isn't always a bad thing.
Thank you for the great game!