A straight forward and fun game.
This game is good old fashion classic doom fun, the game has not lost any of the humour that it had in the other games, and if it could be said it has gained some. The scenes add to this fun with some great areas and characters.
A couple of characters I think where not really in keeping though was the end boss who I thought was boring and unimaginative (boss from the first still the best), and the rocket dinosaurs just looked terrible, like they should be a 4 year old's toy.
The engine has improved (as it should has, its been a while), with great graphics across a large space, these are not the best graphics you can see in a game but when overwhelmed with enemies and being able to see for miles then you have to appreciate the time Croteam has put in to it. They have also been able to squeeze in an adequate and modern physics engine and a better sound engine.
If you liked the previous Serious Sam's then I would say buy this game, but wait till its on budget, it won't be long and its not worth spending all that money.