There are some good things about FM 2015 which might make it interesting for someone who has never played the series before. For me, as a pretty hardcore player, I feel like I'm in a vicious circle just feeding my malcontent about the game, but cannot break my addiction. And hell, I've had many spells of FM addiction throughout the last fifteen years, but they are only truly rewarding when I feel I can make a difference with my particular style of play. And my preferred scenario is the lower league model, excessive scouting, wheeler dealer kind of approach, which is worth very little in 2015.
The thing that works the least, for me, is that I don't feel I can truly play the game the way I would want to play it. My expectation is that somehow getting a few amazing players in a League 2 or Conference team should show. But whether it shows or not depends on chance, player ratings are very position dependent, with central midfielders taking the runt of bad ratings, however amazing they may seem. So I might spend hours searching for the coolest prospects I can find, fishing for work permits for my non-eu conquests, but getting phenomenal players on a mediocre squad matters very little.
The general feeling is of a wooden game. Bizarre things happen which seem to defy reason. Some are buggy, like goalkeeper reactions, some are fixable via lengthy tactical tinkering, like defending corners, and others are the worst of all: monotonous. Long distance goals? Maybe on TV. A fast player outrunning a defender unless the latter fumbles it? Keep dreaming. Half competent goalkeepers seem harder to find than the proverbial needle.
And then there's an aggressive randomness to how a team behaves and matches unfold. My "concede within the first ten minutes syndrome" seems unshakable. I am not saying it cannot be done, but the feeling is that it is something that needs to be fixed from the get go, rather than something that should be reasonably fine under normal conditions, like corners. And when there's a huge quality gap between your players and the opposition, it all gets hard to fathom.
So why have I played hundreds of hours of this? On the one hand, the addiction. On the other, that elusive feeling when things actually do go right and you win an amzing match. But I am left frustrated because FM seems to be going nowhere, the development of the game fails to address key issues year after year. A balanced match engine. A bit of flair and a bit of the unexpected. Some character and individuality to the players. Unbiased ratings. Consistency and logic in the transfer system. Of course it's not easy and there's a lot of back and forth in trying to get it all together, but considering the heritage of this series, I cannot avoid a distinct sensation of complacency, padded with the occasional UI revamp or a couple of shiny new features.
Bottom line: if you have not played this yet, maybe wait it out some more, like until SI decide to take the bull by the horns and create another classic. There are many people who enjoy working on this game and its database is a treasure trove, an inimitable advantage for anyone interested in joining the fray. The risk with taking it up is that even if you get it for free, time costs incurred are not worth the experience and chances are your passion for football will be your downfall, in spite of this.