The most realistic war simulation FPS I have ever played. Occasional bugs spoil the fun, but a great game nonetheless.
The graphics are 9/10, since I consider them more than enough for the large draw distance, but they are not completely cutting edge. The character animations and weapon loadings are very realistic. You have a good quantity of weapons and vehicles to use, and you will take command of your squad of three additional soldiers.
The computer AI is where the game stumbles. Your squad mates will sometimes place themselves on unprotected positions, and sometimes will get stuck on avoidable obstacles. This will make giving orders more difficult under heavy fire, and since you will spend approximately 30 minutes to 1 hour on each mission, failing to complete them because of a bug can be very frustrating (especially on "hardcore" difficulty, since there are no checkpoints during the mission).
Anyway, those bugs are not present at all times, and if you execute correctly your strategy and give your orders appropriately, you will minimize any errors and get the satisfaction that the game can feel as realistic as possible. This is very important when playing on "hardcore" difficulty.
All in all, Operation Flashpoint: DR is a great game with occasional bugs that fortunately will not prevent the game from delivering a realistic military experience.