I am using 6670 since last 1 yr. I feel, its a value for money handset. There are few pluses and minuses though.
Pluses:
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Symbian 6.0 OS and good processor speed. Also thanks to 64MB MMC.
Good resolution of the camera (1 MP), if taken properly images are very sharp and clear.
Document viewer (word, excel, ppts and pdfs), this is excellent feature. With the newer version of QuickOffice even you can edit the documents using phone. I use it a lot. I keep all my interview preparation stuff in here. Thank God, my manager is not reading this review.
Good set of softwares included with the out of the box phone.
Good Phone book
Keypad design is elegent and professional.
Bluetooth speed and transfer speed via cable is good.
Minuses:
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Difficult to read the screen in sunlight.
Bulky, palmfull shape / design.
Weight is also more. Not a femenine phone.
Video quality is something that nokia may work on.
Sound output for the MP3 / real player is mono.
No FM radio provided.
Nokia have worked on some of these minuses in the later version of the phone, the 6680 and 6681. Also, recently Ive heard that nokia has reduced prizes of its sophisticated model 6630 in Feb 2006. It is now available at the same prize of 6670 (atleast in Bangalore). Ill rather suggest to go for 6630 as a best bid provided you are getting it for lesser than 14K.