Enjoyable, but still prefer HeartGold / SoulSilver.
1. I didn't really like the whole atmosphere of Unova.
2. They removed Lv 100 from friend code battles.
3. Barren postgame. After finding the sages that's about it. I would have preferred a Battle Frontier over a Subway.
4. Bare minimum features. Gym Leader rematches with updated teams from all generations would have been good. a Vs Seeker would have made it easier leveling up. Pokémon following you would have been nice but I'm not really bothered by that.
5. Levels post game are messed up, the lack of a Vs. Seeker only made battling more frustrating.
6. Riding the back is awkward.
7. Lack of touch controls.
Some of these things are minor, but my main complaint is the barren postgame content, though there are some good things:
1. Multiplayer expanded. The C-Gear is amazing.
2. Dream World. Being able to get Pokémon online is also amazing.
3. Global Link. I love how we can download new skins for our C-Gear, and participate in Global Battle Union ranked battles and tournaments.
4. Animations & Battle Environments. I like how the Pokémon are fully animated now, and the battle environments also being animated are a nice touch.
5. Weather Condition Indicator. This speeds up the flow of the battle.
6. Story. Easily the best story of the main games. Team Plasma is a constant presence and the leaders actually play a role (aside from the first three) in the story.
7. Reusable TMs. I'm going to admit that I never used most of my TMs cause I could only get one, and getting more of the same was a pain, so they became collectables, rather than things I use to make my Pokémon stronger.
I still prefer Soul Silver over Black though. Better post game, and the whole atmosphere is better.