For me I am happy that they are making these games but what I will say is, it's about damn time. I played through both gold and silver a number of times but my personal favourite was Crystal so this makes me wonder if I should hold out that little bit longer for a Crystal remake.
One thing I thought was great about the origional's was the results you could get from breeding. I once bred a Butterfree with a Venomoth and after the egg hatched I ended up with a Yellow Caterpie that evolved into a Yellow Metapod which in turn evolved into a Pink Butterfree. I have not had great success in breeding different pokemon like this with Diamond and Pearl for example. Overall my point is I hope this feature remains unchanged (unless it's expanded upon) in these re-releases.
Should I wait for a Crystal remake though
EDIT: *POSSIBLE SPOILER*
I just remembered you get to visit the region from the red, blue, green, series, or first series of games after you win the pokemon league. 16 gyms man
*END POSSIBLE SPOILER*