Honestly there needs to be a mixed button for reviews I think. Magic 2015 is a shining example of a game that has a number of good qualities but is marred by some bad ones as well. It's like they took all these great ideas and then put some flaw that ruined the awesomeness that could've been. I'm going to look at both the core game and the Garruck expansion with this review.
On the positive side we finally get true deckbulding. Every card you unlock can be accessed to build any deck you want. This is something people have been clamoring for for awhile and it's great that they finally offered it to us.
You also face a wide variety of different decks in the single player campaign which while showing you the diversity of Magic also unfortunately shows you all sorts of cool stuff that you won't get to use in the game yourself.
I've heard people complain about the black and white color scheme and honestly I don't have a problem with it myself. I think this is a taste thing as it doesn't seem any better or worse than the previous color schemes used in Duels of the Planeswalkers.
This brings us to some of the noticable flaws in the game unfortunately.
First is how they approached deck building. You can have one of any mythic, two of any rare, three of any uncommon, and four of any common in your deck. This goes back to the bad old days of hiding good cards behind rarity. Note that there are good common and uncommon cards in this game and bad rare cards(I can't recall if there are bad mythics off the top of my head) but honestly they should've looked at each card and said "Is this broken?" and if their answer was yes, not included it and if the answer was no then allowed a full playset of four cards. Some games can be decided by someone getting that rare or mythic card in their hand.
Second is some bad campaign choices. This is especially bad in Garrucks expansion. In that you have to use Garruck's premade deck and you'll be facing off against decks that are specifically designed to beat him. It's not fun. It's frustrating. For example the second Garruck match gives you some new cards for your deck that you have to use...such as creatures that are capable of killing a non-black creature.....when you're facing an opponent who is using mono-black. End result is that you have a seriously overpriced 3/3 flyer in your deck. All the Garruck matches are like this and it's more a frustrating slog through the expansion as a result. It could've been awesome. His deck has stuff that you'll almost never get to play in the actual paper game such as Bayous(the original black/green dual land with no restrictions) but they successfully made even that not fun.
Third is the paucity of game modes. I've heard people complain about the lack of two headed giant which is fair, but they pretty much only have the most basic modes. This is the first Magic which hasn't offered an alternate mode at all. No Adversary, no Planechase, nothing. Commander has been big lately, couldn't they have put stuff in for that at least?
Fourth is that some of the starter decks are almost traps. They're really really bad and if you chose one it'll be much harder to go through the main campaign until you manage to unlock a few worthwhile cards. And you don't even get to know what's in them until after you chose one.
Fifth is the lack of other players. The flaws in the game have clearly lead to a limited player base as I've wandered on at what should be good hours and only seen a few people on. The flaws and the fact that apparently they're already working on another game have clearly lead people to moving on.
The last thing is more a meta situation than anything else so I'd say less a flaw and more a flavor thing. Obviously different eras of Magic had different metas. The meta for 2015 is fairly aggressive. It's going to favor aggro decks and not be so friendly towards slower decks so if you want to play a defensive blue/white control deck for example 2015 probably isn't going to be the Magic environment for you.
Overall it's a fun but noticably flawed game. I wouldn't pay full price for it but if you see it discounted(I'd say 50% off minimum) and enjoy card games you might have an enjoyable playthrough. I got it discounted and I do think I got my money's worth but I probably would've been more annoyed if I'd paid full price. So not recommended at full price, but go ahead and pick it up if you can get it cheap.