PMDG established in 1997 is a small software company founded my Captain Rober S. Randazzo that started his business producing detailed airliner manuals. They have evoled and are now responsible for some of the best airliner model simulations.
Somewhere in time, the PMDG decided to develop an MS Flight Simulator model of the Boeing 737 600/700 and released it initially by July 2003. In May 2004, they released an addon pack with the -800 and -900 models.
The PMDG 737 - The Next Generation is a complete model pack for FS2004. It is highly detailed 737-600/700 exterior model, realistic flight model (replaces parts of FS's flight dynamic code), some very well acomplished cockpit panels and a great virtual cockpit.
The PMDG 737 - 800/900 was a released extension for this model. It contained inumerous improvements, fixes and two new models - the -800 and -900. The most notable changes were:
Overall I believe it is one of the most realistic and commercialy sucessful payware models available today. PMDG can be proud of being surpassed only by themselves.
Unfortunately I'm not a pilot of anything, so I can't really compare the flight model with the real 737 or with any other airplane. I can say, however, that it is a very complete model and requires some study to get familiar with all the switches and systems. It is a very rewarding feeling when you know what you're doing and why.
According to real 737 pilots, the flight model is very realistic and the airplane systems respond accordingly to what would be expected on the real aircraft.
It is definately great fun and cannot under any circumstance be compared with the MSFS2004 stock 737 - it is like comparing rocks with oranges.
On the outside, it is outstanding. See for yourself by comparing the following screenshot of a 737-800 PMDG model with a picture of a real Boeing 737-800 at LPFR.
The 737's virtual cockpit was absolutely state of the art. That was before the release of the PMDG 747-400 model... It took a new 747-400 model for the same company to build an even better cockpit, topping only themselves. Let's not forget that this model is over four years old and still has one of the very best virtual cockpits available.
Compare the following screenshot with the referenced real picture of a cockpit and see for yourself.