Conclusion of 1 week with FSX+PMDG 737+FSXWXFSX is old, but IMHO visualy very good sim. With all options tuned to maximum, You will obtain very nice graphics, but unrealistic, because roads infrastructure coming from NAVTEQ's sources 12 year old. In Slovakia, I found only something looks like main highways. Route planing in FSX is poor, there is not possibility to manual enter SID, STAR, or waypoints from airport's charts. Online planners can export flightplan in format, that can be converted to FSX file format, but it is uncomfortable and FSX is payware. In result - night transalps flight like Sion-Innsbruck with high probability will end with CFIT on approach to destination...
Weather - there are some weather scenarios, visualy not bad. But I very missed live weather. In deploy time probably real weather used free Jepessen data, now that data are as payware service. Solution exist - ActiveSky (known for P3D users), but again - it is payware. Or free utility FSXWX, results are very acceptable. This utility creates its own weather grid with interpolated values (baro pressure, wind aloft etc.) and that values feeds to the FSX.
Boxed aircrafts are visualy very good, but functionaly only average. No MCDU for SID, STAR, only something like GPS navigation. Or use old style VOR to VOR flight. ILS autoland is implemented on B737-800 and A321 (not tested). Graphics of that aircraft is decent. On that PC was installed payware addon PMDG 737 NGX contains 737-800 and 737-800. This aadon is next level in the sim - almost all switches are functional, in the MCDU is AIRAC database (today obsolete, but probably updatable from Navigraph). No problem make flightplan, enter all needed parameters and fly from Sion to Innsbruck in totaly dark and foggy night on autopilot with LNAV/VNAV activated
Flight dynamics is reasonably good, FG 737-800YV is very similar with PMDG 737, or fix base simulator at simulatorcentrum (check
viewtopic.php?p=338600#p338600). Default 737-800 FDM is good too, but not as good as PMDG. Default A321 has not simulated FBW, IDG's A32x and 33x family is far better than this one.
FSX doesn't remember last flight settings, You must always select aircraft, airport, time and weather. Very disappoining. There is not possibility for automatic GMT simulation time.
If You can buy FSX with action price 9.99EUR on Steam, it is realy good deal. Standard price 25 EUR is a bit high for dead software without possibility to use high quality addons, this is 32 bit application with limit of 4GB usable RAM. And if I imaginate completely modelled EDDF, KJFK, EGLL, with PMDG, You will hit 4 GB memory limit 10 meters behind the gate. Price for PMDG is around 70 EUR, FSLabs A32x @100 EUR - really high for unexpandable FSX with 32 bit core. But there is 64bit P3D...