Decent enough conversion for an OK sequel, but for me it just didn't have the same nostalgia or popularity as the original Donkey Kong.
As with its predecessor, the game was more difficult than the ColecoVision version, particularly on the second screen. In fact, a friend of mine who owned both hated the Atari version because it was too difficult even for him, and he was a relatively skilled arcade player. However, that aside, at least with the Atari version, when you successfully completed that round, you got the satisfaction of Donkey Kong booting Mario off into oblivion (as opposed to seeing DK raise his arms in victory).
I myself could never get past the second screen until the cheat code for invincibility was printed (I think it was in Atari Explorer magazine).