I've put around 5 hours into the game thus far. I played Mario Tennis 64 to death and loved it. I skipped the GCN version. I've never played the GB versions. Here are some of my observations:
--I quickly turned the gyro controls off. I don't like moving my 3DS to play.
--I felt the single player tournament play started off way too easy. I got to the 4th cup without even losing a set, not a game, but a set. Unlocking the "pro" com players is much better. However, I'm still not finding it difficult to advance. I'm now in the 8th cup and I think I've lost a match twice now.
--Doubles play I haven't touched yet.
--It took me awhile to figure out how to earn coins and I don't like it. Basically, the only way to earn coins is to play the mini-games. There are so many items to buy that you'll have to spend hours playing these 4 mini-games over and over to ever have a chance to buy most of them as the items aren't cheap. From my experience, playing tournament and online earns you zero coins. Not a fan of that.
--Online with friends. At first I thought this would be great. I have 99 friends on my 3DS and I'd say close to 10 own this game (you can tell by the friend leader boards). The first time I ever went online, there was a friend waiting to play and we played 3 games. It was fun although I appeared to be a little more experienced than him. Since that time, I have never been able to hook up with a friend again. It's way too hard to hook up and I now realize how lucky I was the first time. The problem is this isn't like Mario Kart in which you can join in. You have to create a room, and then wait for a friend to show up and play. The chances of that happening are slim to none. There's no way to communicate with your friends to join up, even if they are playing Mario Tennis at the same time.
--Online with strangers. I've played probably 30 matches and lost around 20 of them. I've only experienced lag during one match. The rest have been flawless. I've only played the tiebreaking matches online. Basically, the first to 7 points wins. If I've played 30 matches I'd say 28 of them ended in a score of 7-0, 7-1, or 7-2. The game is supposed to match you with people matching your skill but as of yet, this isn't happening. I'm hoping once you play a few games the matches will be better. It's no fun playing someone you have no chance of beating, or someone that has no chance of beating you. To make it worse the items you equip are carried online. It's very easy to get matched against someone that already has bought the dominant items which makes it even tougher to compete if you haven't spent hours playing the mini-games to earn coins.
--This game makes me grip my 3DS so hard my thumb is usually throbbing after a play session. Not sure why I keep doing that.
--I also wish you could take the touch controls off the bottom screen (which I never use) and replace it the scoreboard. There have been several instances in which I had to go to the pause screen to see where we were in the match.
Reading through this probably indicates I hate this game, which I certainly don't. I enjoy and look forward to playing. It's just frustrating that it appears corners were cut. I agree with most of the reviews. Good game that could have been great. Feel free to discuss.