The best of its kind... shame it's never been localized.
For me, this had everything a Digimon game wanted: challenging yet fair gameplay, a wide range of potential Digimon partners, and a genuinely fun mechanic that made collecting interesting.
Lost Evolution has it all, sans an English release.
It's a shame, really, because this game may well have revitalized the franchise in English-speaking countries. The game gets moving pretty quickly, with some brief exposition before being flung into the action. Only a few minutes in, you'll already have five Digimon and be set to explore and obtain others. Even without being able to understand the plot, I got a rush from the most important thing I get from a video game... fun.
That's what this game is to me, sheer fun.
The plate-cleaning mechanic can be a bit frustrating at times, but you'll get better tools to make the process easier, and I get a genuine sense of accomplishment with each new plate inserted into the evolution tree. The fact that there are less recolors and more original mons, not to mention any Digimon can, with time, become any other one, adds to the customization that Dawn/Dusk laid the groundwork for. Plant Digimon are now their own type, while attacking elements have been reduced to the four classical elements (with electricity in place of air) plus light and dark. The enemies created for this game are fun to fight and have cool designs, especially the final bosses. This game has a lot of nods to earlier Digimon works, including fights with characters from the previous two DS releases.
As mentioned earlier, there's a huge range of Digimon to team up with. You can have any partner from the show up to Savers, most of the Royal Knights and Olympus Twelve that had been released, Kowloon Co., the freaking Sovereigns,
the Ancient Warriors... and that's just the tip of the iceberg. The clunky DNA Digivolve mechanic has been removed, and Digimentals are placed on the tree and don't require a trip back home.
I feel like this game streamlined what Digimon World DS and Dawn/Dusk did and made this into a very respectable Digimon game. My only complaint is, of course, the lack of an English release. Of course, there's still a slim chance with the dubbing of Xros Wars on the horizon, but for now I'd recommend finding a Japanese game if you really want to play... which any longtime fan likely will.