Mass Effect 2 leads on directly from Mass Effect (but not crucial to play the first before the second, but is worthwhile to play the first game) and can take your save games from the first game into the second, to continue your personalised Mass Effect experience. Characters you had killed in the first game, are gone from the second, choices in the first game can lead to new pathways in the latest game, and combined with a amazing story, that sci-fi and action fans will love, Mass Effect 2 is a thrilling adventure that I couldn't stop playing.
In terms of gameplay, they have dramatically improved it over the first game, with tighter controls, more action packed gameplay. Superb quality for a RPG game, which took me about 30 hours to complete.
The graphics are superb! Amazing HD graphics, from textures on the suits, to the explosion of the grenades, they look amazing! And the sound of the guns, to the amazing orchestral score sounds magnificent, perfectly suiting each situation. Also the voice acting is the best I've ever seen.
The free DLC promotes the life of this game, but it is more the choices you make in the game, which changes which way you play, I've already finished it once playing as a good honorable player, but want to play it again from the evil side to see how it plays out.
As whether to get the normal edition on the collectors edition, I loved the first game (even with it's flaws) and the collectors edition was worth the extra $20. The art book is interesting, however a tad short, bonus ‘making of’ documentaries were very interesting, plus wallpapers, and a great tin case, in a box which has one of the best box art I've seen. The extra armor/weapons aren't game changing, the game has plenty of content to keep you going.
Overall, if your looking for a RPG adventure game, a sci-fi experience, or a great shooter, Mass Effect has you sorted, with amazing visuals, top voice acting, awesome gameplay, I can't think of anything wrong with this game, and is definitely up for Game of the Year in my books.