I started watching it a while ago, and it's not unwatchable, but it is pretty pulpy crap. The action's enjoyable enough, but the conspiracies are stupid, the characters are mostly annoying, and the philosophies are pretty unpalatable.
-Oliver: Can't do emotion, whenever he narrates (Like the start of the episodes) it's grating.
-Digg's entire character arc is obvious from the get go.
-Oliver is a hypocrite regarding his sister, but she's also incredibly annoying, her depression/addiction thing is insulting to anyone who's got firsthand knowledge of either of those things, and the whole "Oliver is out of touch with his family" thing goes way too long, and too stupid.
-Oliver is obviously the Hood. To everyone.
-Considering how often they spell it out, the main story isn't that complicated.
-Laurel's annoying, and the romance plots are goddamn irritating, fucking sexual tension, drama, love triangling "Will they won't they" forced conflict crap.
-Compulsory Detective with a grudge (Who happens to hate Oliver and The Hood).
-Psuedo Martial philosophy "Guns are weapons of emotion, a bow is the weapon of an expert" or something. *vomits*. Because using the bow makes you superior? Better hope the guy who fights with a blunt paper clip doesn't come along. You'll get nailed.
-Constantly running in to beat up enemies with his wooden bow, rather than shooting them. Looks so very silly.
-Never gets hit by sprays of full auto gunfire from multiple guys (Yet when the plot demands, he'll be shot by a novice marksman with a pistol, when he was able to see them and they were unarmed (They had to get out the gun, and then shoot him. Oh god it was stupid).
-Bullshit about "Good/Evil" with the purple chick, and the nature of revenge and justice, which just makes Oliver completely incomprehensible and entirely hypocritical.
-Oliver happily murders or badly wounds henchman (Arrows are fucking dangerous), but always gives their bosses a chance.
-Slade seems to think teaching Ollie to only fight hand to hand is a good idea, and dismisses guns, gives Oliver a gun and tells him to shoot him, and demonstrates that he can take it off him. Good thing guns don't work at a distance, eh?
I know I've listed a bunch of negatives, but it's an ok show. It's just a really flawed one. It could have been excellent, but instead it's just average. The island bits are fun, Digg is awesome, Slade is cool, the action scenes are fun, the Robin Hood style vigilante stuff's fun, but it's not exactly Breaking Bad or Game of Thrones. It's more in the league of Big Bang Theory or CSI.