Yes it is, without spoiling anything, here's a quick summary:
You are a human, you've always been, you have a Pokémon fellow and you travel around the world completing quests to prevent large threats from ever rising, when one day during a quest to stop World Destruction you decide to time travel back to the past and save the 'Temporal Tower' from collapsing, where Dialga rules and controls time, the time travel goes wrong because an uknown being interferred and now you've been transformed into a Pokémon. You remember your name and the fact that you were a Human, but you've forgotten who your partner in the future was and what your quest was at all. You befriend another Pokémon who helps you out to recover your memory, and so you do. You become an explorer team, a team which saves Pokémon in distress from dungeons and arrest evil Pokémon, when eventually some *spoilers* ... happen, and the rest of the story without going any futher is just so messful with your emotions, many dilemmas going through your mind when you're not given any options, sacrifices, and goodbyes.. I wish I could talk more about it but it would tell too much about the plot. If you like Pokémon, it's a must try it out.