The problem with TNG is that it didn't necessarily get better in linear fashion, the way one could argue that DS9 got better as it "found its voice" and established a continuous storyline. TNG has some high points and some clunkers in almost every season, though there are slightly more low points in the first two seasons. Having recently rewatched the run of the show, in chronological order, I'd guesstimate that 10% of the episodes are bad, 50% are decent, 20% are great, and 20% are spectacular. [1]

So something like this would be especially helpful for TNG, where a) there are a lot of episodes in total, and b) there are no useful rules of thumb or shorthand (such as "skip season X," or "it gets better beyond Y").

Now, the great news about TNG is that it's mostly episodic. Which means she can watch any episode, at random, and enjoy it as a self-contained story. (Aside from the two-parters.) TNG really lends itself to randomized viewing. DS9 needs to be watched in chronological order (at least for the first-time viewer). TNG can be watched in any order.

[1] Some people will find this assessment overly generous, and others will find it overly harsh. That's the beauty of Trek fandom; there's plenty of room for disagreement. :) Just about the only things TNG fans can agree on are that: 1) Riker with beard > Riker without beard; 2) "The Naked Now" is probably the series' worst episode, although it's enjoyable in a kitschy, ironic sort of way; 3) Wesley Crusher sucks (although Wil Wheaton himself is a pretty awesome guy).