There is one big issue that doesn't come across when watching on Youtube - a weird, dog whistle-like high pitched sound permeates throughout play, which I found painful to listen to unless my volume was low. It's most noticeable during the few seconds before a new stage starts or when dots are collected. It's possible that this is an emulation issue; MAME is paradoxically precise enough to preserve artifacts that would have been dropped by the low-fi TV speakers of the time (or the streaming compression algorithms of today), or perhaps by the Atari's own analog circuitry.
I didn't spend a lot of time playing Ms. Pac-Man. As impressive a port this is, considering how bad the first one was, it doesn't offer much over the arcade original which is now readily accessible in so many different forms. The game does feel easier than the original, which I don't prefer, but I didn't spend much effort trying to find out if this was because of different ghost AI, or a more forgiving maze layout, or for other reasons.
One thing that surprised me is the relatively few game modes, which up until now have been so common in Atari's console games. Pac-Man had eight of them, plus an optional and as usual pointless two-player mode, and used difficulty switches to affect power pill duration. Ms. Pac-Man has no two-player mode; a good call considering the memory-prohibitive cost of remembering two different maze states, does not use the difficulty switches, and only has four game modes. All that the extra game modes do is reduce the number of ghosts in the maze, which I suppose may make it more accessible to easily frustrated children (the extra modes are denoted with teddy bears rather than numbers), but to me it only serves to make it less interesting to play.
GAB rating: Good. This is an excellent conversion of a great game, and tends to be overshadowed by its predecessor's infamy. Had the Atari 2600 ever been my only video game system, I'd consider it a must-own. It's a bit ironic, that the wretched Pac-Man port was the best-selling game on the system, while this game, which is everything it should have been and more, barely sold a fifth of its numbers.