I got to 100, and I don't see why people think it's hard... Overall, it's just another td game. Hard to rate it without a biased opinion, so I guess a 4/5 for lack of originality.
Great game. The only thing that bothers me is that the save thing says "Save and Exit," so I never saved because I didn't want to exit. So when I died, I had to start over. I'd change it to just "Save."
For some reason when I start a level, it lags for a few seconds. I've played this before at onemorelevel.com and it worked perfectly. Don't know why it's lagging.
First off, I noticed that the strange lag happens when something dies/when you place a unit. Also, I tried switching browsers, but it didn't work for me.