City fan in New Jersey. I'm a Red Bulls fan, but since I live so close I've had a very good look at NYCFC.
The founding of NYCFC was met with a lot of excitement and skepticism. A lot of people immediately jumped on the ride, while many others said the team was merely a marketing ploy for Manchester City and they didn't care about growing the MLS. NYCFC hasn't really done much to change this belief, many people say that their DP purchases reflect their focus on branding first and football second.
That's not to say branding is a bad thing, NYCFC are winning the battle off the field. Largely due to their Yankee connections NYCFC have immediately gotten their brand plastered all over NYC. They have a large deal with sports chain Modells, which has their shirt on display right as you enter the store. If you go to their official websites and look at their partners/sponsors you will see that NYCFC already has more than RBNY. And with primarily New York based companies. Even the mayor's son is wearing NYCFC shirts.
That's not to say they haven't messed anything up. The Lampard fiasco was an obvious PR disaster. It doesn't look to have created any long term problems, but at the time it destroyed NYCFC's reputation around the MLS. The biggest worry that NYCFC was merely a Manchester City branding tool was proven correct in the minds of most supporters. That along with the ridiculous stadium restrictions, and the whole "crud" blunder, has given people the perception that NYCFC fans are mostly there for the brand and entertainment, not the football.
This is further solidified by the fact that the football hasn't been good. A midfield pairing of Pirlo and Lampard is just too slow to defend and it always leaves their defenders open. In MLS there is a salary cap in order to maintain the level of competition between most teams. However, each team is allowed 3 designated players (DPs) who's salary does not go against the cap, in order for MLS to compete for international stars. It's how Beckham was able to join the Galaxy. NYCFC's DPs are Villa, Lampard, and Pirlo. They're old and except for Villa, don't really seem like they care. And although it's too early to give any definite analysis of their impact, they've been fairly dire, barring one Pirlo assist.
In retrospect I would say NYCFC have had a lot of growing pains, but the future doesn't look too bad. Yes, on the field the team is not good. And there have been a number of PR blunders by the FO. However, the brand is rapidly growing, they are attracting huge crowds to every game, they have owners willing to spend, and none of their problems look to be long term. (Except for the stadium, but I didn't put that in as it isn't completely their fault. NYC's mayor doesn't seem too up for the project) One thing I feel that really encapsulates the impact of NYCFC is how it has re-invigorated many of the RBNY fans who haven't been as interested for some time. You could also look back to the New York Derbies and see just how passionate the fans were. The Red Bull Arena has not been louder all year.