Problems with hybrids:
Highway mileage is unspectacular. Hybrid powertrains use tricks to get better fuel economy which work best in stop-and-go driving. (Regenerative braking, shutting off the engine) On highways, they aren't much better (if at all) than a comparable non-hybrid car.
It may not pay for itself. Depending on how you drive, and how much you drive, the amount of time for the fuel savings to add up to the additional cost of the hybrid powertrain can vary from a couple of years to a couple of decades.
The batteries wear out, and are expensive. Unless you just dump the batteries yourself, they're probably going to end up being recycled, so the environmental cost isn't that high, but the monetary cost will amount to a few thousand dollars, most likely. That said, the Prius can do well over 150,000 miles on its batteries, the Honda Insight was/is able to do over 200,000, and some hybrids can run just fine without their batteries holding a charge at all. (Some, however, cannot. The Insight can, the Prius cannot). This cost is going to come down over time, but it's always going to be big.
Studies that have claimed hybrids have higher costs than gas hogs tend to be highly biased. One commonly cited study compares the R&D costs of conventional vehicles to Hybrids, neglecting the time difference involved and the inherent initial costs of new technologies. Ignore anyone who tries to claim this point, they are full of crap.
Anyhow, if you live in a major city and don't do a lot of long road trips, yes a hybrid is a good idea. If you mainly drive on highways, though, no, it is not a good idea. You will not be making the most of it, and would probably be better served (and be serving Earth better) either buying an economical used car and keeping it in good repair, or buying an economical NEW conventional car, like a Yaris or a Fit or something, and keeping THAT in good repair. (but used is the best choice, environmentally)
Oh, and if the EPA lists a particular fuel economy number, that number CAN be achieved. Even the old, higher numbers. You just can't be a leadfoot and expect to have your car sip gas. The driver is as important as the car in determining fuel economy.