Pilot episodes can be tough to judge a show by, especially in terms of the structure of the episode. Because so much has to be introduced and explained, the first episode may not be representative of the flow of the show down the line. However it is a good means of judging the characters, and on that front there's a lot of promise in "Constantine." The show follows the comic book character of the same name, an exorcist and battler of demons. At the start of the show he's checked himself into an asylum, not because he fears that the demons and spirits he sees aren't real, but just because he's desperate to forget them and he figures drugs and electro shock might do the trick. The universe has other plans though, and he's soon on the road to try and save the daughter of an old friend.
Matt Ryan definitely looks the part, but he also nails pretty much everything about the character. He's world weary, yet has a strong moral compass. You get the sense that he wishes he could just ignore the things he sees wrong with the world around him, but something inside him won't let him just walk away, and that annoys him. He's not out to impress anyone and yet maintains an effortless sort of swagger. He knows what he's confronting is dangerous, but he's also seen it all before. So he's flippant while still making the hazards seem genuine.
Another thing this show does well is make it clear that just knowing Constantine is practically a death sentence. Seriously, if you see this guy coming up to even say "hello," just run the other way. He means well enough, but the world he treads in is so dangerous and follows him everywhere he goes. It's something that's important to the character and how he operates and is well conveyed in this first episode.
The actual "case" he works in this episode isn't really anything special, but it's about what you'd expect in a pilot episode. It gets the job done in terms of showing the sorts of things he deals with, and it has enough moments that let the audiences in on why Constantine is the way that he is. The female character who he's protecting isn't much more than serviceable. Thankfully after the test screenings she was written out of planned future appearances. The way in which she's removed from the show is a touch ham-fisted and awkward, but it gets the job done and has her still fulfill the function she was going to be needed for.
Whether or not this will be worth tuning in for on a regular basis is going to largely hinge on the next couple of episodes. It's a world and a character worth spending time with, so the question is whether or not the stories being told are any good. And that is not yet entirely clear.