Is it good choice or is it bad choice? The question itself is missleading. Why? Well, US obviously has terrestrial needs that are primary to all other and this does make sense. On the other hand, I think that abandoning the constellation program is not such tragedy like "abandoning human spacefligt forever", that sounds pathetic. What is this, you ask? Well Constellation is infact, apart from being costly, pretty bad approach on returning to the Moon, not to talk about Mars.
First of all, two launchers? Why? Back in the 60's they only needed one, it was on the edge of possible and it worked! And now, 60 years after, NASA needs two! Tech got pretty good from back then, infact a quantum leap was acheeved in engeneering, design and electronics. All suggests that things should got smaller, sophisticated, compact... No, we need one launcer for the crew, other for the fuel, third for the solar panels, fourth for the supplys, fifth for... and all of theme are different in design, well not so different but enough different to quadruple the cost. Orion? Look's like back to basics, nothing smart happened from Appolo... is this really happening? Don't missunderstood me, human, or manned spaceflight is crucial! Man was up there and will be again, however not in this fashion. I think the lack of enthusiasm in NASA is a result of overpumping the price to heavens for nothing. You don't get inovattive, you don't get anything, you are just so expensive! So the best thing is to ask the private sector to do it for you, cheaper. Constellation, I fear, looks like the NASA plan to send a man over to the Mars 10-15 years ago (that ended up in a recycle bin), by first: building a new space station, then building a series of complex building on the moon, then building a spaceship shipyard in the Earth's orbit and so on.....that would take VAST TRILLIONS of dollars and would be completed in a million years....rubbish! Let's not mixup manned spaceflight with robotic exploration. Robots are waaaaay cheaper in all aspects. All of that before (new space station, moon base complex, shipyard....) sounds fantastic but when you wake up... So president Obama's cutting the Constellation off is that wakeup call. Yes, NASA is fat! It's NOT nice but it's real.