Precious - doesn'tshow her talent too much, but I'm impressed she was able to do album at that age.
First love - I don't like most of songs. She couldn't pick singles better, "Automatic", "First Love" and "Movin' on Without You" are really the best.
Distance - Hikki has improved her style, nice album with pop/rock songs.
Deep River - experimental, seems like she finally wrote songs in the way she wanted too
Exodus - well, some songs are perfect (Kremlin Dusk, Animato), but some are awful.
Ultra Blue - beautiful ballads mixed with more up-beat songs (This is Love, Keep Tryin'). Still experimental, but not as much as Deep River.
Heart Station - the most emotional album, and the most personal, I guess.
This is the One - Utada tries to go mainstream. A way different from her japanese work, however, it's still better than lots of dance music we can hear on the radio or tv.