Bots and toys
By far the most interesting, and difficult, vehicle is the helicopter. DICE has done an admirable job of portraying the basic flight characteristics of choppers, which are quite unnatural. Adding throttle only moves you higher; to fly forward you need to tilt your helicopter forward. Hitting A or D will rotate the helicopter with rudder controls, but moving the mouse to the side will tilt it sideways, making it strafe. This makes flying a helicopter an active mental exercise, and your first few starts will help explain the abundance of crashes these temperamental beasts have in the real world.
Realism again takes a back seat in favor of gameplay, since helicopters are considerably more durable than aircraft, but this is to compensate for their slow motion and the ease with which they are hit. One of the more useful things certain choppers can do is to pick up cargo. While you may wonder where the laws of physics have gone when you see a Huey flying around with a Patton tank chained to it, there's no denying the dramatic effect of a tank being dropped in behind enemy lines - or even firing at enemies while still airborne.
Since the master server wasn't up yet, we spent most of our time with the bots provided by EA. While they're not as competent as the UT bots, they are a marked improvement over their Battlefield 1942 counterparts. There are still instances when they'll stay in one spot or circle pointlessly, but the problem isn't near the same degree as it was with the earlier incarnation of this franchise. The bots are capable helicopter pilots, crashing more than an experienced human but nothing too egregious. They actually have some human traits as well. For example, some bots enjoy taking a perfectly good transport helo, flying off alone (leaving their teammates behind), and over enemy territory, where they eject, parachute and leave the copter to crash.
An equally great improvement has been made with the sound effects. Battlefield Vietnam sounds as good as Call of Duty, which is a real surprise - I didn't expect anyone to come close to Call of Duty for quite a while. Every effect you can think of has been updated, from pistols and rifles through tank guns, to the big explosions. You can even hear the shell casings from an M60 machine gun hit the ground.
We'll have a full review ready soon, after the online community has a chance to form and we can fairly judge multiplayer. Stay tuned!