Ok first thing I want to say is that I really enjoy that you have a barrel blast level in each world. I am totally on board for that approach. However I felt Factory was not as good for a few reasons. http://imgbox.com/eIMWCv4T
I didn't feel as though the Mini Necky's fit in this level, especially as they are never seen again. I would rather have more barrels/platforming/Krusha's (in that order) rather than Necky's in general. I liked the jumping Kremlings leading into this though. http://imgbox.com/efqjK68q
This is my least favorite part of the level. I don't like getting shot from a barrel into an invisible snake (just before this picture) and the strangeness of snake behavior in this whole section in general is frustrating. The barrel above the snake spawn feels a bit silly but its also easy to lose input on top of the snake spawn and run off the ledge. Again I would rather see more use of barrels (barrels into tires and fire pit platforming is cool imo). There is a section of barrel blasts that follow this that includes a rotating barrel moving along the y-axis you are suggested to shoot NE out of that I really liked. Just past that is adult Necky that spawns sorta funky sometimes and again feels a bit out of place in the level imo.http://imgbox.com/nrhIv10F
I don't like this entire platforming section, but this dip down with a random Krusha sticks out like a sore thumb especially. This platforming section is barren and boring, and a rather long stretch of it considering this. Snakes are fine here but the rest is meh.http://imgbox.com/IxPqmMRa
The barrel section following includes this barrel-bee sort of limbo that I didn't enjoy at all. The correct timing doesn't feel intuitive at all and its further complicated by the fact that if you miss the correct timing there is almost no window open for you for ages following the miss.
Overall I sort of just wanted more barrels going in weird directions with a bit more fire and tire and less open space platforming. I wouldn't mind seeing Krusha (or Mega Krusha) however.
EDIT: I don't know how to format pictures, added url links.