It's not Chinese speaking. They do have English speaking guides. The tour does largely cater to Chinese speakers though.
As someone who has taken this 4 day tour I will tell you that it's not worth it. It's terrible for a vacation. You are up at 6 and on the road at 7. You spend most of the time on the road, only to pull up in front off major attractions to take a quick picture.
It basically caters to the stereotypical shutterbug tourist who has no interest in even touring any of the attractions. For example, the first day in Boston we were dropped off for about an hour near the harbour. Not much time to see anything. Next morning they showed us the campus of Harvard and MIT. I would hardly call that a grand tour of Boston. In New York, the stopped off in front of the UN buildings, drove past Times Square and offered tours of the wax museum and Rockafeller Center. In DC, we stopped on a roadway cutting through the Mall, just to take a picture with the Capitol in the background. Then they rushed us through the Smithsonian that has the hope diamond in it. In Philly, they take you to the park with the Liberty Bell, but of course they don't give you enough time to actually line up and get to take a picture with the bell inside or to take the tour of the old courthouse. That should give you an idea of what kind of tourist experience you'll have. It's for people like my parents (who dragged me on this trip) who now claim to have seen Boston, Philadelphia, New York and DC after going on this trip. Tai Pan is for people who just want a picture to say they were there.
Also, be forewarned. They will tell you that they are staying at top hotels like Hilton, Sheraton, etc. They stay at their lower chains like the Hilton Garden Inn, Four Points, etc. in locations that are usually in the suburbs of places you are visiting and usually far from any access to public transit. We drove 45 mins into NJ after our 'trip' through NYC. Though me and my brother would have gladly taken the subway back into town for a night out, it was simply too far and cumbersome from the motel we were at.
The last issue I had was with food. Though this is probably not an issue for most people. In every city they basically stop in Chinatown for lunch. There's no real effort to let you try local foods and specialties. No New York pizza, no seafood in Boston, no cheese steak in Philly. The rest of the food stops are highway rest stops or third rate restaurants in suburban big box plazas.
The best way I can sum it up would be to give you the equivalent of a trip to Toronto. So you'd spend hours on a bus early in the morning to arrive at the SkyDome and CN Tower at 10 am. They would only give you 5 minutes to take a picture in front of the attractions. Then they would bus you to some cheap and relatively quicker attraction like the Ontario Science Centre, then take you for lunch on Spadina somewhere and start making their way out of town. Along the way they would point out Nathan Phillips square, the Eaton Centre, etc. and then drive out to a Hilton Garden Inn in Markham somewhere. There you go, you have visited Toronto.
I did it once (mostly because my entire family was going). I'll never do it again. Was a waste of my money and time. But if you want a drive through experience of a city with minimal planning effort Tai Pan is perfect. My suggestion, pool together with friends or use a hostel to stay in a city. Then use a hop-on/hop-off tour service. Far more enjoyable. Don't get swayed by the whole 'you get to see 4 cities for only 230 bucks gambit'. You get what you pay for. For Tai Pan prices you get what you pay for and deserve, a drive through cell phone camera worth photo tour of 4 cities with cheap motels and average food along the way.
