You know, I liked the cute little monsters, merely because it enabled Donna to see the lighter, non baby-killing side of the Doctor. I think this was a must, because for the mate, the Doctor needs someone who trusts him, not who is afraid of him.
I also enjoyed the comedy and Donna. I am a HUGE Catherine Tate fan, and I loved even her serious moments. I love the buildup of the Donna charactr. The mistake they made with Martha is that she had a TON to live for... she was an aspiring Doctor, and a family who loved her, despite their own fighting. When the Doctor invited her as his mate, it was kind of like... why? She has such an intricate life. With Donna, just like with Rose, her life is mundane. She NEEDS adventure, she NEEDS to see the universe. It's as much her needing to get off that planet as the Doctor needing to have a friend. I think that this series started off brilliantly, and I can't WAIT to see the rest. YAY!