So, after about an hour of playing, I finally reached (and, consequently died on) the Titanium tier. I feel I've played the game enough to get a good feel for the update, and jeez, it feels completely different. Previously, I felt it to be a bit "bare", what with the lackluster number of enemies. Then I found myself being chased by literal waves of enemies (see below). You definitely weren't kidding when you talked about the difficulty of higher tiers.
One of the best parts of this game, that separates it from otherwise similar games, is the dialogue. The original dialogue was humorous, entertaining, and diverse, and this update didn't disappoint. When the announcers started talking about Spider-tron 6000, I knew I was in for a world of hurt.
On that note, a couple issues I found:
1. Occasionally, melee robots (I've only noticed the tier 1 robots doing this; I assume it's because of their simple movement pattern) will stack on top of each other.
2. To begin with, I found the jetpack somewhat hard to use; for some reason, pressing SHIFT then A/D + LButton comes to me with difficulty.
3. This was a small problem in the last version, but has become much more apparent in this version: especially in later stages, the bow is almost useless. The only hits you can score are lucky potshots, which consume energy you need for getting away from tier 2 jetpack bots. I feel like it should be buffed to hit things easier, either with increased projectile speed or some sort of "homing" function.
4. This is a pretty minor thing, but I'm a recovering grammar Nazi, so it bothers me: One of the announcer dialogues contains the word "picnic", which is subtitled as "picknick".
That was my two cents. Hope it helps. Keep up the great work!