Two steps forward, one step back... The graphics and overall interface are as they've always been: Attractive, simple, and functional, although somewhat less so now that you've come up with all of these upgrade paths and the experience bars. The gameplay is kind of frustrating to me, though.
I like the overall increase of upgrades. It puts a lot more emphasis on the strategy of the game, and allows players to make a lot of different choices. What I don't like is that you have to unlock these upgrades through experience meters... To me, this just seems like a way of making players wait longer, making progress more linear, and making that progress arbitrary. Although the system works, it has a certain 'feel' to it that I'm really not sure I like.
It feels a lot like the Bloons series has gravitated a lot more toward the mobile market, which isn't necessarily bad, but means that the gameplay is appealing to a different audience, which means that a lot of features have been added, but what these added features COULD have been has been dumbed down a bit.
Overall what annoys me is just how I feel like the game is holding my hand, giving me a pop-up every time I unlock a new feature, or flooding me with easy levels. I finally quit when I lost because of the lead camo level, which was just about one of the cheapest ways to get a game over. My overall response to this game is that it's reached a point where now it's just trying too hard. The game is still good, but the spark is gone now.