Well, I have to say that Pokemon Black 2 and White 2 are cool games. The Pokemon Grey thing seemed predictable, plus sequels are basically original to the main game series, with these games being the sequel to Pokemon Black and White and Pokemon Gold/Silver/Crystal being pseudo-sequels to Red/Blue/Yellow. The cool thing is that Black/White Kyurem seems to be the strongest pokemon in the entire saga next to Arceus, with a stat total of 700 compared to Arceus' 720. The thing that has me is that before the English release, people thought that Kyurem was used by Ghetis as a murder weapon against the hero, but then again, Ghetis is by far the most evil of the team leaders. While the other leaders only intended to steal pokemon and awaken legendaries, Ghetis wants to be the only person to own pokemon, so he corrupted N and now, he tries to incapacitate the player. I would advise watching out for his Hydreigon. That thing wiped out my team three times in BW (even when my Stoutland is at Level 60+). Of course with it being in level 52 instead of 54, his Hydreigon should be slightly weaker now.

As for Iris, I know that Alder retired from championship, but who let her become the champion? Anyways, Iris, by far, has the craziest outfit of all of the champions. In RBY, Blue looks basically like a normal trainer. In GSC, Lance wears what seems to be the outfit of a dark prince. In RSE, Steven Stone wears a simple suit-and-tie outfit while Cynthia from DPPt wears a black, knee-length winter coat. Alder, the former champion, wears clothes that the typical American Indian chief would wear minus the feathered crown. Iris, maybe she became excited over the thought of being the champion, note the hairdo, tiara, and elaborate dress. As for her team, it's funny how she still has Haxorus when she has Mr. Wipe-Out-The-Entire-Team, aka Hydreigon. Guess what? It's at level 57, and with the same moves that Ghetis' Hydreigon had back in Pokemon BW. She's going to be difficult indeed.

Well, that's all I have.

I enjoyed my playthrough, though I wish that the main plot had been longer. Leveling up pokemon is still a very big pain as well.

I'd recommend getting whatever version's sequel you had, so if you got White originally, then you might want to get White 2, or vice versa. There's some continuation of the plot depending on which version you choose, but if you don't care about that sort of stuff, then you should just pick whichever version has the most exclusive Pokemon you like.

Yep.

I got White 2 to match my Black 1, to get all the version-exclusive areas (not Pokemon) I didn't get the first time around in Black 1.
Honestly, it really doesn't matter too much, since the differences between them are minor at best. However, there is the Key System. If you know friends around you (not over Wifi) have a certain version, you'll want the opposite so you can complete each other's key collection. If there isn't anyone, then here's the list of keys in each:

Black 2:
~Normal Mode (available by default)
~Challenge/Hard Mode (gotten after you beat the game)
~Black City (available by default, but only transferrable after you beat Area 5 of Black Tower)
~Regirock (available by default)
~Registeel (available after you catch Regirock)


White 2:
~Normal Mode (available by default)
~Assist/Easy Mode (gotten after you beat the game)
~White Forest (available by default, but only transferrable after you beat Area 5 of White Treehollow)
~Regirock (available by default)
~Regice (available after you catch Regirock)

Only one "Mode", one "Area", and one "Regi" key can be active at any given time. Also, these aren't the names the game gives these keys, but those are the effects they grant. (The names are slightly different in some cases.)