It's not inconsistent if it's been there since day 1.
What, just because it exists, it's automatically "consistent"?
You just didn't pay attention.
I have paid far far more attention to this dumb show than is healthy for me.
First: over the last year and a half in this forum, I've acquired a genuine dislike for the term "hater" in connection with anything and would prefer not to see it used here, and especially not when aimed at another poster.
Ah don't worry, when you actually know the difference between good writing and random crap, people who don't have a clue call you a "hater."

I have also been called hater of:
ENT, VOY, BSG on occasion,
Dollhouse, Fringe, Defying Gravity (well everyone hates that),
Stargate and amazingly
DS9, just because I didn't think it was 100% perfect. To me, it's a mark of distinction and a testament to my discriminating good taste.
Granted, Temis and others are perfectly fine to dislike the show (hey, no problem--it's not their flavor of entertainment), but I would like to see specific evidence supporting facts (I'm from the BuffyForums school of dissertation-length story analyses)
Just jump into any
Heroes thread this coming season, I'm sure that you'll get a bellyful of supporting facts unless the show undergoes an amazing improvement. Our threads over the past three years have been long rants of facts, and lately they've been followed by, "that's it, I'm bailing on this garbage." How have you managed to miss these discussions? Check SF&F when the series premieres. If you want to uncritically defend this show, you will attract a whole lot of folks willing to give you a good fight. Lately the threads have been nothing but, "this is crap, goodbye, I hope it's cancelled," so having someone willing to mount a defense would at least be different.
As for what's wrong with the show, where do I start? Here's some stuff just off the top of my head:
-Hiro is pointless; he's an overgrown child playacting at being a hero, which is revolting to see in a grown man, especially when his nonsensical hero fantasies endanger peoples' lives or even the entire friggen planet.
-Claire is pointless; she pingpongs between loving her Daddy and feeling betrayed by him. She needs a character arc of some kind, any kind.
-Niki or whoever she is called now is pointless; she's just there as eye candy but the actress is a bore and they've never found a reasonable role for her to play that justifies her existence in this show.
-Far too many plotlines are introduced and unceremoniously dropped. Good writers don't introduce plotlines unless there's a plan for them. Nathan's religious conversion. Peter glomming Sylar's seeing power. Hiro endangering the world simply because he's bored. Claire's magic blood, which has been forgotten when critically injured characters like Nathan could have used it (Sylar's blood should also be magic now, too). All that stuff in Ukraine, was there a point? Hiro and Ando went to India to what, stop a wedding so a lesbian couple could be happy? What does that have to do with anything? The whole New Orleans saga went nowhere. The comic book store plotline was obvious filler. And remember Peter's Irish girlfriend? Apparently he just left her, lost, in some alternate future, and didn't even have the common courtesy to mention that he feels bad about it. Or something, anything. The writers cannot just dump a character like that and not expect us to notice!
-Far too many plotlines have no payoff or insufficient payoff. Hiro's Japanese journey was a bore; Peter's soujourn in Ireland was pointless. Matt's African journey - so what? Arthur Petrelli - bust. Sylar's dad - another wasted opportunity. Sylar being a Petrelli had no purpose, so why even bring the subject up? This show has become a collection of random go-nowhere plotlines.
-Too many characters are written inconsistently. Mohinder for example. How can this moral guy be so easily manipulated into experimenting on people? How can this supposedly smart guy be so dimwitted as to experiment on
himself? Now he wants powers desperately? Not so long ago, he was counselling Nikki to be very leery of powers, since they were so corrupting.
-This series isn't about anything. What it could be about is obvious - the timeless problem of people having power that they lack the wisdom to wield properly. But the writers would actually need to construct a story arc and character arcs that support that theme. Right now, there is no theme, just a bunch of stuff that happens, followed by other stuff. That's not a story, that's a mess.
Basically, this show is a catastrophe. What's amazing to me is that I'm still willing to watch it. That's because I really do like some of the actors, and sometimes a train wreck really is entertaining.