I loved Doom 3 when if first played it through and I kept going back to play the odd level hear and there, but ROE is just rubbish . Apart from being very short (yes I know its an expansion pack) the game just throws everything it can at you towards the end of the game, and it just feels dumb, I even found myself activating god mode, not because the game is impossible, but because I got bored with its use of big nasties, and it just gets worse the further you progress into the game. On reflection I could have probably used the new artifact more, but then that makes you invincible while it is activated anyway.
The end boss is Dr Betruger and he is certainly no where near as good as the final boss in Doom 3 and actually spoils the game a little because with the three other bosses through ROE there are some tactics needed to defeat them, but Dr Betruger just needs pulverising with the rocket launcher.
Even if you see ROE in the budget bin, I wouldn't recommend it. It doesn't bring anything new and is just a poor imitation of the Doom 3 singleplayer game. With stuff thrown in, but with that being said, almost all expansion packs disappoint. So their probably isn't anything the developers could have done to make it better than what it is.
3/5