Katrina Kaif tells you why BlackBerry Curve 9220 is a great buy - YouTube
If your experience with Blackberry 7 is great in itself than your fine, if you want more for your experience then wait for Blackberry 10. :)
I believe for most of us, we DO want Blackberry 10! :D But Blackberry 7 is still a great OS that should not be quickly abandoned as it can still be used for those that do not have a need/demand/desire for something like Blackberry 10.
By the way, I been looking at getting a Curve 9220 or Curve 9380 off of ebay while I wait for a good line up of Blackberry 10 phone's, and this makes a good cheap upgrade so I can be up there with everyone else using Blackberry 7. :)