It doesn't help a great deal, either, that the player you create is a bit of a chump at the start. Beginning with a zero-star rating, the only way to improve is to beat opponents - either in one-off matches or through tournaments. Winning points and games (even when you lose the match) will eventually contribute to your star rating, but the problem is just that - winning games is disproportionately and unfathomably tough.
As something of a tennis gaming veteran, I kicked off on the game's medium level to see how I got on, but was forced to drop it down simply to see if I'd fare any better. The difference was minimal, and, again, the problem was nearly always down to actual shot-placement rather than fierce AI. In the heat of a lengthy rally, you might be doing fine, but one misread shot and you're another point down. If that happens a couple of times in a game, you're not only left frustrated, but probably defeated. The AI hardly ever makes mistakes. Being able to unlock special moves, such as Serena Williams' serve, by beating them in one-off matches is largely inconsequential when the outcome of so many matches is apparently random.
As you might expect from EA, 23 of the game's major stars have been licensed, and it's these pros that you'll be facing throughout. But unlike most other tennis titles, the focus isn't entirely on the current crop. So alongside the likes of Andy Murray, Roger Federer and Serena Williams, you get old stagers like John McEnroe and Pat Cash popping up for another crack at Wimbledon. Impossible, obviously, but it does add a smidgen to the overall appeal to be able to play against the stars of the past as well as the latest and greatest. Another interesting decision is the cartoony visuals, which are obviously meant to be in-keeping with the Wii's house style, and look nice enough. It will be interesting to see if EA sticks with this for the other versions when they turn up.
Similarly, it will be interesting to investigate these games again when both players are using the WMP. Right now, you're either going to have to shell out GBP 20 a pop to find out, or hope that your friends are willing to part with the extra cash for the slightly-better-value bundled versions. In these early days of the WMP, such issues are going to be moot for many.
And in Grand Slam Tennis's case, they may be entirely moot. Grand Slam Tennis is an underwhelming representation of tennis, crippled by unintuitive controls, and just makes you want to go back to the precision of Top Spin or Virtua Tennis on a control pad. You can't blame Wii MotionPlus for this failure, because it's almost impossible to tell whether it's helping or hindering. What you can say is that Grand Slam Tennis isn't very good either way. Bring on Wii Sports Resort.