My take is, this is the best I've ever seen a young quarterback play despite having consistently low yards per attempt and yards per completion figures.
I've generally been big on QBs pushing the depth of the passing game vertically with intermediate to long throws. I like a guy with a high yards per completion number, a guy that can throw accurately and consistently at 20-25 yards.
What I've seen as the season has wore on is, he's making a lot of those throws, and he's also making a lot of the right decisions considering where this ground game is at, decisions that should win us football games. He's just not getting much help from his receivers.
It's been interesting watching the guy build on his game from week to week. You can see a visible progression. A flaw in his game springs up, he works on it and fixes it by the next week. Taking sacks is a good example (gets sacked unnecessarily against the Jets, then goes two games without taking a single sack). Fumbling the ball when hit in the pocket is a good example (fumbles the ball a bunch against the Bills, hasn't fumbled since). Making risky decisions with the football is an example (made a risky throw against the Chargers in his first action, and didn't earn another interception until 6 games later at the end of the Buccaneers game).
I also think that one of the remarkable aspects of his game has been his ability to perform in comeback moments at the end of games. You can toss the first Bills and second Jets games because neither came down to any kind of closing comeback moment. But, look at the closing drives at the end of the first Jets game, the Patriots game, the Saints game, and the Bucs game. Look at the throws. The drives didn't all succeed, in fact only 2 of the 4 drives succeeded in their aim of coming back and either winning or tying the ball game. But if you look at the throws and the decisions, the decisions were right and the throws were flawless. Against the Patriots and Saints, our receivers just let us down. They couldn't hang on (primarily Ted Ginn), or they made dumb decisions (whether it be Camarillo's deciding to throw a fumble out of bounds to try and cheat the clock, or Hartline running a wrong route, etc).
What he needed to get better at, and again this is very interesting because it's another example of something he's been building on from week to week, is playing with a lead at the end of these games. They were trying to maintain a 34-31 lead in the fourth quarter against the Saints, he throws three straight incompletions and the Saints take the lead on the next drive. Not all of that was his fault, that was another example of him making a nice throw or two and his receivers dropping it or screwing up in some other way. But in the second Jets game, we're trying to maintain a 30-25 lead and he not only can't convert a first down, he took a very unnecessary sack which put the drive at -12 yards and gave Sanchez a better chance at that go-ahead TD (which never materialized, thank you Randy Starks). Then of course you have the Buccaneers snafu, he's just got to know that you don't take a chance on a tight passing lane when you're protecting a touchdown lead with less than two minutes remaining. You can't do that.
But you know what? Look what he did against the Panthers. He improved on this aspect of his game. The defense started to let up in the fourth quarter...AGAIN. The Panthers pulled to 17-14. The chips were way down with the OL injuries guys shuffling in and out, etc...and look what he did. He makes that huge play on 3rd & 12, a 15 yard gain which put us about 10-12 yards away from FG range. Of course, Ricky Williams heard none of that field goal talk, finished it off with that 46 yard run...but the run doesn't happen if Henne doesn't have that brilliant rollout where he bought more time and found Bess uncovering from the mess.
I think overall the guy makes 25 yard throws look like 15 yard throws for other QBs, from both an arm strength and accuracy standpoint, and that's a really good trait to have physically. When it comes to the mental aspect, he still has some things to learn in terms of situational awareness...but that really is something that comes with experience. But he's tough as nails, learns from his mistakes, doesn't generally throw the game away, and seems to perform even better in comeback moments.
Good quarterback. We'll see where he gets on from here. His risk factors as a pro will be lack of mobility, the occasional situation unawareness thing could persist as you never really know, taking unnecessary sacks, there's a possibility that he never earns the kind of ability that guys like Brees/Manning/Brady have to call the offense from the line based on what the defense is showing, and there's the potential injuries as he fought through a fair number of them in Michigan and his toughness dictates that he'll take hits.
One thing that has concerned me which I just alluded to is he seems to not be trusted with a wide array of calls at the line to counter what a defense is showing. Some of the play calls have looked very curious. On one down they'll pass into a cover two look and on the next they'll run into an 8 man box, that sort of thing. We don't know what kind of latitude Henne has at the line to make option calls or audibles, but if he has a wide latitude then he's not making the right calls, and if he doesn't have a wide latitude you have to wonder why.
