I stayed at the Renaissance Beijing twice - for six days in May 2011 and five days in June 2011 and was really pleased with the experience. The rooms were nice, the service excellent and I had no complaints during my visit. To be fair, I did not have lunch or dinner at the restaurant.
Free internet if you are a Marriott Rewards member. No? Enroll on-line before you travel to China.
A nice advantage is that the hotel is just off the 3rd ring road and is a quick ride to and from the airport. Be sure to take directions to whatever hotel you are using (in Chinese) because the taxi drivers sometimes say they have not clue where to go. Ripping off tourists is common. A taxi from the airport to the hotel reviews is about 70 rnb.
Have a great trip!

Stayed here recently for a night.

While the hotel is fine, its certainly nothing special. I think other folks' reviews have nailed some of the key points:
- The room itself was spacious and well appointed, though it showed some age. It was pretty clean, but not spotless. I didn't, for example, take a bath, just because I had an "eh" feeling about how well it would have been cleaned.
- There's a funky odor in the hallways that permeates the room. Honestly, its almost urine-smelling, which is pretty offputting.
- The restaurant was ok, but again, nothing special. Walk across the street and eat at Kro's if you want western, or Bellagio.
- The bar is equally "eh" and service was weak.
- Like most Marriott's, you have to pay for internet (which is ridiculous) and there's no wifi.

Bottom line is that its one of the weakest Marriott properties I've stayed at in China, and you can absolutely do better in Beijing. Unless you were hellbent on being in that particular area, I really don't think I'd recommend this hotel.

I was here last week in March. I had a big, nice room and free access to the excutive room (free food and beer). Lounge has nightly entetainment but not too many people there. If you miss American food like myself, the Crow's nest across the street has decent pizza. The pool is very nice and the gym is decent.

When visiting the markets always remember to negoiate the price a lot lower!

Stayed here 2 nights for a conference which was also held in the hotel. Since I am a Marriott Rewards Gold Elite member, they automatically upgraded me to a spacious 2 room suite, well equipped but the furnishings were aging, especially the work chair was too low to be comfortable. The bed was comfortable and linens were good, though.

Breakfast in the hotel was decent in both selection and quality. The restaurant is small for the size of hotel so it was crowded during peak breakfast hours. The buffet food served during the conference was bad though, with stale breads and bland, uninteresting selections. Across the street from the hotel is a strip of local restaurants and Chinese fast food noodle shops.

The fitness center was reasonably sized, with a selection of machines that were somewhat dated but still in good working condition. A bigger issue is that there are only 2 elevators serving all 12 floors of this hotel, so sometimes there was a long wait to get downstairs. Service was pleasant and professional.

Overall, not a bad hotel, but the Hilton Beijing down the street is newer, more stylish, and an overall better experience for the same price.