Decide for yourself whether or not to get Black and White, but these are my thoughts.
[start rant]
1) Nob will
not be involved in making the English script (he worked RGB to Platinum, quit before HGSS)
Using HGSS as a basis for what BW could be like:
- Distinct grammar errors.*
- NPCs think you've been to somewhere else if you haven't. (ie. Olivine port = Kanto)
2) Shortened story element which means more filler events, more aesthetic changes
3) Pokemon Musicals = Pokemon contests without battles, reliance on touch screen.
4) More Wi-Fi elements, replacement of Global Trading Station
5) Team Plasma: think Amish group that wants Pokemon to have more freedom.
6) Blend of American, Chinese and Japanese elements in the physical appearance of the Pokemon and story.
7) It's like the old games were Stadium 1-2 and the newer one is Colosseum, it just gets more focused on battles and less on story.
* = (I dare you to talk to the people in the National Park that have script changes from GSC. See if you can make sense of what some of them are saying.)

Please note I have not played the game so I cannot fully judge this game in it's entirety, but this are my thoughts on the matter.
I think the main thing, through all this is personal preference, maturity and age.
When the creators go out to say that 'this is a new Pokemon'... I wonder what they mean.
Do they want the player to still be required to do what they've always done...?
1. Fill Pokedex
2. Own your Rival
3. Complete the Gymleader Challenge
3. Defeat the Eite four
4. Defeat the evil Organization
When GameFreak and Creatures have the potential to make an end-all-of-end-alls, or really change their structure, they should do it. They should go all-out and make the game so drastically different that the players feel that it is entirely new.
Make it violent, make it mature, do whatever they can. Or make it childish, change the setting, place it in the past or in the future. Do more with what a handheld offers, and what technology is available, without compromising those that can't use WiFi or play with others. It's not like they don't have the money or backings to do such a things.
As far as making an end-all, a small cameo of Cynthia doesn't seem to cut it when there are so many pre-existing characters that can be strengthened. If they're going that way, they should back up the 4-generation history of these games and capitalize on their hard work, not downplay it!
I think the company may be afraid of change or losing their appeal to older gamers (like myself), thus a game that is a half-half of old and new. I would hope that they'll really set us up for shock and not follow the formula, but maybe that's what the spin-off games are for...
The Pokemon themselves look interesting-- sirboulevard stated that Gamefreak hired the Digimon artists so that might have effected a small change. I just don't feel the whole thing is unified. It has potential though.
I do think they should evaluate how they are spending their time so Pokemon doesn't fade away like countless other series.
I am not looking forward to a future of same-elements-played-out-a-different-way-followed-by-special-version-and-then-remakes-of-past-versions. They really have no more excuses now that RSE is technically compatible with the newer games, save battling.
I would want to see the story and characters expanded upon, not simply the Pokemon you can catch or the graphics that increase with time. HGSS fared pretty well, granted I still haven't finished the game -- But I'm really enjoying what they have done.
Imagine for a moment if they'd followed a timeline and placed years after GSC! What would happen then?!
Play out Celebi and time warps and all the crazy other stuff that the creation of those Pokemon has provided.
....I was thinking they may have done that for Pokemon X D but I was mislead.
It's something they should really consider, and I'm not talking about some smack-down with all the characters like FF's Dissidea had done, a real story would be nice, thanks. -_-
[end rant]