Disregard my previous comment: I've found that the boats and tanks need MASSIVE amounts of firepower to kill them, and are hardly worth the kill. Changing the rating to 5/5.
One complaint from me: Some targets (Like the ships and tanks) CANNOT be destroyed with a reasonable amount of firepower, or even at all. (I haven't killed one yet). It doesn't make sense to me to have a target that fires back, blocks shots and does not die. It's blocked me from plenty of targets, from escape routes, and from getting extra cash. This is seriously annoying, and has forced me to only give a 4/5.
Protip: Use Magus. Get an item that gives Heal. Run through the entire level and get all the enemies behind you. Heal as needed. Ignite the entire group of enemies. Mop up what's left.
Repeat.
Surfin' along just fine. Lv's 1-28 w/ only 4 deaths. No big deal -Lv 29 comes along-
Ooh, fancy.
-Die
Heh, kinda' expected.
-Die another 500 times
FFFFUUUU-