I have two cordless nailers, both from Dewalt. The first, and favorite is the 18G DC 608. I've had it for nearly 5 years, and it has proven to be a workhorse. With fresh 18V batteries it will install trim far faster than I'm capable of. It's been used to trim every room in three homes, and is a "most borrowed tool" in my stable.
On the other hand, I have a very disappointing DeWalt DC 690. I've yet to get reliable framing nail delivery from this junk. It drives nails too deep, too shallow, bends them, and jams all from the same magazine into the same board with zero adjustments. Simply put, it won't drive nails repeatedly. I would sell it on Craigslist, but I would feel guilty about ripping someone else off. I bought it while I was working overseas, and by the time I returned home (and unboxed it) the refund/return period had long since passed. I have read that DW is now offering a two speed version of this tool, but after wasting $400 on the useless one, I've passed on it.
I would highly recommend the 18V, 18 Gauge cordless driver from DeWalt. I would stay away from the framing nailer though.