It's not 'worse', it's 'different'. And it's most certainly fun to play.
It's easy to spend hours defeating the quests in this game, and even after beating the game once you will most likely still have quests to beat. And between completing the quests, you'll be harvesting fruit and raising monsters (who range from mildly useful to complete garbage depending upon their species) which passes time quickly and is surprisingly entertaining.
The characters in this game are actually surprisingly compelling, considering the significant cast. Bud and Lisa, aspiring sorcerers, really make the player feel welcome when they return to their avatar's home to save, and the characters who follow you among the main story routes like Elazul are equally interesting, albeit a tad shallow. Unfortunately there is a completely opposite side to the spectrum, which includes characters that defy all laws of nature (the most alarming of the examples that comes to mind is Teapo, an anthropomorphic teapot from Domina town) and tend to say things that make very little sense, cutesy characters such as the Dub Bears who might appeal to some players but will be sure to irritate others, and profoundly useless characters such as Pearl, who while in your party can neither attack or use magic and provides a wholly un-stimulating response for the second player.
Speaking of the second player, the multi-player in this game, while not nearly as immersive as the multi-player in Secret of Mana or Seiken Denetsu 3, still provides a great experience considering the severe lack of cooperative multi-player games. Provided the second player is not stuck with Pearl (see above) the second player experience remains just as good as the experience of the first player. The second player, if they own their own copy of the game, can even import their main character from their own data file within the game of the other player.
Unlike Secret of Mana, Legend of Mana is simple. The battle system, rather than being oriented about levelling up weapons or spells (it happens, you just don't really notice or care) is more of a beat-em-up game. And it's an easy one. Upon procuring a soundtrack of the game I came across a very short and completely unfamiliar tune, despite my clocking of 80 hours. It was extremely frustrating, so I looked up the title- it was the Game Over music, and I had heard it perhaps twice throughout the entire game. This game is definitely easy.
All in all, Legend of Mana is really fun. It isn't particularly like Secret of Mana- in fact they're astonishingly different, so if you're looking for a continuation of the series, you will be disappointed. As far as RPGs go, if you're willing to enjoy the company of (or ignore the existence of) some horrifically deformed and anthropomorphic creatures like a walking, talking, stained glass window and a rhyming pelican mailman, then this is definitely a game to play.