I've been a big fan of the Lego games from the start, and I was thrilled when they announced they were making a Harry Potter version. However, I was greatly disappointed with the first one (years 1-4), the DS version was very simplified compared to the console one, and I was frustrated when I saw how much I was missing on.
Years 5-7 on the other hand, is brilliant. There are so many things you have to do in order to complete each level. Being able to use the pets for example, or the spectrespecs... The characters on screen are bit bigger too, so you can actually see who you're playing with, a delight when it comes to custom characters. They also added a "duelling club" which gives you the opportunity to duel against all the characters from the game.
I saw some negative reviews focusing on the lack of proper "DS" interaction. Honestly, I'm not a big fan of the touch screen, so I'm glad that the developers decided to put that aside and instead give us a more complete experience of the game. I can understand why people who already have the console version would find this annoying, but it's great for those who only have the DS one.
The only downside is the dreadful quality of the cutscenes, but apart from that I am very happy with this game.