I'm a big boxing fan so purchase as many boxing games as possible. I bought this because of the 'Showtime' in the title, anticipating a good game. 'Showtime' are a company in America who show big time boxing. Unfortunately this game lacks appeal once you start playing it. The controls are okay but it was the "cheap" feeling the game had. There are not a lot of punches to choose from and you will most likely just choose to hit the head with the same punch over and over. The graphics are pretty poor, it has a look of a budget game and same for the audio. In my opinion, it's ridiculously overpriced and deserves to be in the £10-£15 price range.
The game has no replay value, you may play it a couple of times and never go back to it again.
I actually think Wii Sports is the best boxing game on the Wii and that's free with the console!