Hmm.... there was already a thread... in the QNA section. Search for it.
I like 6600 personally.
But it too has disadvantages.
- no FM/Mp3 playback (but can be done with third party spftwares)
- low speaker volume
- slow processor (but with more memory of MMC it's a bit faster)
And with k700i, we have:
- no expandable memory
- bad keypads (IMO)
- no symbian OS
- Night mode cam quality is not that good
- compactibilty issues
So see the pros and cons and decide. I personally will go for 6600