Was curious and did some checking up on this movie a ccuple months ago...
Forgot the link, (should be easy to find with a search of "Wimbledon the movie") but someone created a blog of their experiences as an extra during the location filming on the grounds of Wimbledon last year. Some interesting stories there.
Many of the reports from people who attended test screenings a few months ago said the screener (sneak preview before final, final touches) wasn't so great. A few said it was charming. Many reports on the tennis itself seemed to suggest it wasn't so great and there's an insane amount of diving volleys. I think someone also said something to the effect that the protagonist plays like the top 4 seeds of the tournament (which wouldn't make sense in real life, right?). One comment I found funny was how someone said the movie seemed to suggest that sex is a great way for your wimbledon match preparation. Just some of the gossip anyways.
But setting a US date of September doesn't bode well for the confidence of the execs in marketing this film. If the execs had huge hopes for this film at all, I'm sure they would have stuck it in around May or maybe even mid-June (though it would have to fight with a lot of box office giants at such a time). July's probably too tough for romantic comedies in general (huge blockbuster season).
I personally enjoy Bettany's performances in recent films. BTW, Jennifer Connoly just had his baby (I think they're married). Adore Kirsten Dunst (odd though that the most adult role I've seen her play was when she was a child--Interview with the Vampire).
The CG Tennis looks.... interesting.... in a funny way (I'm guessing unintentionally funny). I guess the visual effects crew did a good job of animating the CG ball and doing their best to make it coincide with the "strokes" of the actors and actresses. In a way, it works (at least to casual eyes). In another way, those are some good balls coming off some funky strokes (but the strokes don't look absolutely horrible, they just look "different..."). The let-chord ball on the trailer almost had me laughing off the couch. At least it looks like they spent a decent amount of time trying to get the strokes looking close to right.
For more information on the production of the film (and more rants by Pat Cash who was consulted for this film *semi-cringe* check http://www.tennisweek.com/