Christian Bale is the 3rd person (movie wise) to play John Connor. I must say that I was a bit affected (effected? I can never remember which) by his little rant on the set months and months ago. My favorite John Connor was played by Nick Stahl. Maybe not the most popular choice, but my favorite.
I do know (per EW) that Christian Bale was originally wanted for the part of Marcus Wright but ended up wanting the role of John Connor which makes great sense if there is another movie, he'll still look like John Connor.
It was a great movie and I'm glad that I saw it. Would I watch it again? For free. I won't be adding it to my collection, but I haven't bought any of the others either.