It's not terrible so much as it's not good.
Even the consensus worst entry int he series, Partners in Time, at least significantly changed/added to the battle system.
Dream Team does absolutely nothing new in terms of battle mechanics beyond a couple annoying motion control limit breaks, and the battles are sparser and easier. The overworld is completely boring and corridored. The game is 4 times too long.
Just to offer a counterpoint, I really loved Dream Team (I realize I already mentioned this on the previous page, but I wanted to expand on it a bit). Yes, this game has plenty of tutorials, especially early on. If I'm remembering correctly, the original two Paper Mario games aren't as tutorial-heavy in comparison, and to be fair I haven't played the original SM RPG yet. Still, I think there's quite a bit of greatness on offer in this game, although I realize this is not the most popular opinion, especially coming from someone who actually really dug Sticker Star. I found the Giant Battles just as epic and challenging as any in Bowser's Inside Story, the Dream World just as overflowing with creativity as Bowser's Insides in the same game, and the sidequests as plentiful and satisfying as in any previous Mario RPG I've played.
I realize the game has some of that handhold-itis that puts plenty of players off, and that its length exceeds what people are usually going to be expecting in a game like this. But I'll tell you, I played 55 hrs of this game or thereabouts, and there's still some sidequest stuff I didn't get to in my first full playthrough, and still, I had a big grin on my face the second two thirds of the game. It took 15-20 hours for me to really get into it, which I realize is quite a commitment, but once I did, it really held my attention and impressed me with its creativity. I enjoyed the game up to that point, don't get me wrong, but it was only once I really felt like I was getting into it more seriously that I felt like I had a better appreciation for its merits. Anyway, if you're in the mood for a game like this and have played and enjoyed the other M&L games, I strongly recommend it.