I've never completed the game so I'm anxious to get it again (originally had to sell my DS). Is there anything worth it? I love collecting anything Skyla related so that's that I guess! --- She turns around like a tornado! http://i.imgur.com/oJhWKGQ.gif
Pokémon Black and White are my favorite pokémon games. To be honest, you will be restricted to just Unova pokemon up until post game. Some people find this off-putting.
This game is more story involved with each of the gym leaders (bar the Striaton trio) having some sort of involvement with the plot.
As for anything being worth it, that would be a bit subjective. Are you talking in relation to transferring to XY/ORAS or in general. Since items are a no go, and the Dream World is now invalid (Why GF puts 25% of game content online, I'll never know...), you are quite limited in the BW games:
Reshiram/Zekrom, Kyurem, Terrakion, Virizion, Cobalion, Thundurus/Tornadus, and Landorus are really all that is left of value. Keldeo, Meloetta, Genesect, Victini, and Zoroua/Zoroark were all event related, and you can no longer obtain the plethora of HA females, Arceus event, and DW Mamoswine and Banette.
It's really limiting in that regard. Post game has a few extra areas with: Anville, Lacunosa, Undella Bay, Black City/White Forest, Transfer Lab, and a selection of previous gen pokémon. You can also battle Cynthia in her vacation home in the summer (or was it spring), and you can fight a GF staff in Castelia.
Most of the above does sound a bit of a downer, and it is, but I personally found BW to be the most engaging and enjoyable to actually play through the main campaign. It also does not require heavy use of HMs. Just like with XY, HMs are optional.
There is not a lot to collect that is unique, and Skyla does not have too much of an involvement after her gym 'arc'.
All in all, the sequels have the better content due to the truncation of the online servers. It's still a fun game, but only for the main campaign (E4 battles and Cynthia rematches). --- [This signature is currently under construction]