I can only speak for myself, and have to say the -700 is a joy to fly. The automatics are very similar to -300, but the presentation and the displays themselves are extremely good. In many ways, there are a lot of differences between the two, however mixing the flying on both types is no problem, we often fly both types in the same day.
So yes, the differences are noticeable,in lots of ways (try getting a -300 to climb at 3000fpm through FL350!)and without a doubt I prefer the -700 every time.
Regards,