THE GOOD:Graphics are smooth and seamless, no more polygons. Battles are no longer sporadic, instead they are replaced with constant interaction. A more in-depth storyline, and more cards make this game way more fun than the original.
THE BAD:
LK2 is still short for an RPG. I would like for it to have at least 30 hours of gameplay minimum, just to finish the main quest, and maybe 20 extra hours to collect everything. Nothing other than that.
SUMMARY:
From Software really improved on LK1. It seems as if they heard what I was screaming at my television when playing the first game 
LK2's graphics are now nearly seamless, using the GCN's graphics to the best i've ever seen in a 3rd person view game. Now instead of all the polygonal shapes of the monsters, and characters, they're all smoother, more life-like. Gameplay has also vastly improved, the player being able to shuffle through his/her deck, instead of having to drop cards to find ones he/she wanted, like in the first game. Transform cards allow you as the player a little action, instead of having to sit back and let your cards go to work. Also summons now have dual options, giving you a choice as to which attack to use in different situations. Combos add to the creativity of this game, as well as all changed abilities of old cards, and brand new ones.
The only complaints I would have are 3.
1. Some cards you only have a couple chances to get. If you miss them then, they're gone forever. Examples are boss monsters that you need to capture (using the all new exclusive "Capture Cards"), hidden treasure chests that become unavailable, and cards that can only be gotten through upgrading cards that you can't get, like the ones above
2. Sound is well, basically unheard. None of the battle tunes stick with you, except maybe the boss one, and that one gets annoying after a while. None of the level songs are close to matching the calibur of Final Fantasy, or other top-notch RPG series'. Although many of the voice-overs are nice, they're only heard during cut-scenes, not in the actual game, where i bet they would be most appreciated.
3. The game is just too short. I have only about 12 hours of game time, and i'm nearly finished with the game. I would love for future LK's to have at least 30 hours in the main quest alone, and maybe 10-20 hours in side quests/collecting cards. Although this is probably quite difficult, thinking of ideas for stages, and building stages, I believe it would be beloved by a vast amount of people, especially the hardcore fans from the first game, which took 6 hours to beat.
Overall, I absolutely love this game. When I got it, I just couldn't stop. I'd play for hours and still not want to stop, until my fingers stop functioning correctly and I'd hit the wrong card buttons
. For newcomers, I would recommend only renting this one. It's short, and unless you get addicted, it's not gonna take longer than a couple 5-day rents to beat. If you have LK1, I would recommend buying it. That's because you're probably hooked on the game, and also you can download your LK1 cards into LK2 near the end of the game, letting you see your old cards in action again.