To start off, I'm going to clear some misconceptions.
This OVA, in my opinion, is heavily targeted towards the audience who have played the game. For a 4 episode anime, it clearly does not cover many significant aspects of the actual story, as you would expect. Many reviews, including external resources out of MAL, disregard this important matter and criticize and how lacking the anime is.
For fans who have played the game, such as myself, it is an extra treat. Tales of Phantasia could easily be seen as one of the best Tales series out there, but you won't get the appreciation out of it through the OVAs, but through the game.
The animation is great, especially the battle scenes. The theme songs, especially the ending theme, "Prayer" by Masami Suzuki, really gives you a very emotional feel that will leave you feeling mixed emotions of sadness, hope, and tragedy; at least that is what I felt. I really love the song.
As I have played the game, I know the actual story, and I truly appreciate this story and animation.
Some people say that the characters are typical cliche fantasy characters, but these characters are, undoubtedly, very well presented. As you may have guessed, do not expect to see much character development; you get all of that in the game.
So in summary, if you have played the game, I greatly suggest you watch it, but do not watch it for the story, as the OVA is very slightly different than the game itself. Watch it for a recap and to appreciate the characters coming to life as it is very well illustrated and it creates a truly memorable "Tales" experience.
For those who haven't played the game, but still wish to watch it, go ahead. This animation has the qualities of a great anime, but being only 4 episodes long, the plot is greatly reduced, and is heavily ignored/criticized by people who have not played the game. It is truly a shame.
I give the ratings I give only because I have played the game, which makes my rating biased. But I also believe it is because I watched this anime expecting it to be a recap and only to see the characters coming to life, not as a series.
If you have the time, I suggest you play the game. The Super Nintendo (SNES) version you can find is the Japanese version of the game with unofficial translations, but the translations are cleverly done and quite enjoyable. The GBA version of the game is just horrible,voice acting especially, although the graphics may be a little better. I suggest the SNES if you do wish to play. Do not underestimate this game just because it is old.
1) For fans of the game = Must-watch
2) For people who have not played the game = Highly recommended to appreciate the animation, but not the plot, as it is rushed.