Hi - I recently upgraded from the Alpha A300 to the Alpha A65. I've also got the Nex C3. 
With regard to the A65, there are a bunch of new features that I really like. In no particular order, the ones that stand out most are:
- the camera feels solid and well built.
- the new position of the on/off switch - much better!
- the FPS - this is great at sporting events.
- the rear screen - I like the way you can flip it around to protect it but wish it would swivel in both directions!
- white balance - easy access via view finder, which makes it easier to make adjustments and see the effect immediately.
- finally, and most importantly, the camera feels great when I'm using it.
With regard to the Nex C3, I've been really pleased with it. It's lightweight and easy to take on short business trips. Again, here are some key factors:
- I like the design and the build feels solid.
- the programmable buttons on the rear make it easy to access frequently used functions.
- the picture quality is great and it seems to work well in low light settings.
- I like the colour filters - they allow you to do some fun but simple things without any post production.
Hope this is useful.
Stuart