Whether it's worth buying is subjective. If you like rhythm games, and are a fan of retro DJMAX stuff (though there's a shitload of new media, including BGA for tracks that didn't previously have them, etc), then Trilogy probably would be worth the money.
It's been more than half a year and I'm still not completely done with the game. The button layout, while based on the PSP releases, is significantly different from O2Jam and obviously different from IIDX (Muse-on controller can go DIAF) in terms of how the charts are built.
On the other hand I know more than a few people who have put the game down/sold their copies. Did they get their money's worth before that point? Maybe.
Sure it sucks that the plans fell through, but them's the breaks with how unstable the eastern music game scene is other than Konami realistically. What's left as a legacy is a PC game that's still 100% playable, even if the general consensus is it could have done with a lot more charts. I'll give another example - If Pentavision completely folded over and the hope for a new title was zero, would the four existing PSP titles still be worth picking up? Definitely.
Keep in mind that from what FE posted on his blog, most of the additional features seem to have another price tag attached to them. While it obviously sucks that most of it seems canned (I'm assuming NieN and PlanetBoom would have gone nuts with the Rock expansion) those costing extra is a very different perspective from "Oh, you get only half of what you pay for when buying DJMAX Trilogy because you won't be getting all the promised updates". Those promised updates would have cost extra. You get what you pay for when purchasing the Trilogy box.
Things aren't over: I don't doubt that in a few years we'll see another PC release (or a continuation/engine upgrade of Trilogy) with all the current CQ/BS tracks, and we'll be reminiscing about how Trilogy died the same way we talk about how DJMOnline died. And yes, I know FE not being in Pentavision anymore changes things. There's still a lot of people left in the industry who know how to make games, though.
It's really all about a passion for music/music games overcoming what has shown historically as a financial failure or at the least a question mark. That, and the will to get things done/make a change. | 
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