Bargain alert! This is a ridiculous deal as you'll get Serious Sam 2, Serious Sam 3: BFE, Serious Sam Classic: First Encounter, Serious Sam Classic: Second Encounter, Serious Sam Double D, Serious Sam HD: The First Encounter, Serious Sam HD: The Second Encounter, Serious Sam HD: The Second Encounter - Legend of the Beast, and Serious Sam: The Random Encounter... i.e. all of the Serious Sam ever, basically... for seven quid.
Personally I'd recommend it without hesitation. Serious Sam is one of my favourite series ever, a brutal and ridiculously satisfying all-out brawl with huge levels and hundreds of monsters, along with the biggest set pieces in gaming history. Thanks Buzz!