Not enough love for this game. This is a must-have for any TD fan. I spent countless hours on the browser version (original and bonus levels) and the game is just superb. It is very tightly balanced, and I only had one major gripe when I played it in Flash, and that was the inability to reveal stealth units (besides attacking them early on.) Some maps seemed just impossible to get a gold medal on for this reason.
Thankfully, this is somewhat fixed in the iOS version, as you can purchase the ability to see stealth units via IAP. Though I'm not too fond of this all or nothing approach, because it kind of makes it too easy once you get the IAP.
Overall, this is an excellent game. Yes, Kingdom Rush might look shinier, but there's no reason to just get one game. If you're a TD fan, don't skip this one!