This part is what people usually read expecting you to tell watch it or not worth it but that's impossible. People have different tastes. Kampfer is full of fan service. If you want an anime where you get to see cute, big breasted girls fight for no particular reason then go ahead and watch kampfer. If you want to see a harem where everybody likes the boy and seduce him 24/7 then go ahead. If you are looking for an anime with a good plot, good action and good romance, please reconsider if you decide to watch it.
There is absolutely nothing to it. If I could change the title I would name it "The Life Of Natsuru Senou". At first you could tolerate it. Tolerate seeing girls fight with each other for no particular reason but then a few episodes through and you are wondering, "What the hell?". It makes no sense at all! Though there are some clues that tell you that there is something a lot more deep to the girls fighting each other but then there is nothing.
Backing up my previous statement on changing the title to "The Life Of Natsuru Senou". There isn't decent romance in it but most of the time when the girls are not fighting they are seducing Natsuru. That's where it was enjoyable. Seeing big breasted girls fighting over a boy. XD!
So we have established that the plot is only about a boy getting seduce by cute girls(Oh! He can change into a girl for some reason they never cared to mention) but there is actually no romance and there is mindless fighting.
This is one good point in this anime. The quality is fantastic and the art is outstanding. It's enjoyable to watch. I didn't really look out for animation but I just know that the characters are well drawn.
The sound is fair. it is not corny but not particularly excellent.
Maybe they had too many characters but you never really saw them to the fullest. The main character was like an insignificant toy(then again there would be cute girls without him). You didn't see much of the other characters either.
Finally, it was very enjoyable. There were laughs. The art was good. Just another typical harem that hardly makes sense.