The sole reason that I would ever say anything along the lines of "This game reminds me of (insert name of another game here)" is because it's a lot faster than describing each game aspect and how it works.
Would I say that Blur is what would happen if Need for Speed: Carbon (racing game), Wipeout (the weapons system) and Call of Duty 4 (the mods system) were mixed together? Yes.
EDIT: Okay, so it seems Battlefield 2 did the perks system first, but the only BF game I've played is a small bit of BF2142's multiplayer, so please excuse me for my lack of knowledge on that subject.
Would I say that Blur in any way, rips off, clones, copies or whatever's any of those game's aspects? No.
I've noticed that the only time the word "rip-off" is used is when one game does one thing first, then another game does it later and gets very negative critical reception and the only time the word "clone" is used is when one game does one thing first, then another game does it later and gets average/above average critical reception.
Yet, none of those words are ever seen or heard when someone compares two games that have been well-received. Hmm, I wonder how that works.
Also, I've been playing far too much of the Blur beta demo lately since the netcode was fixed and it stopped resetting my rank after two games, so it's the first game that came to mind as an example, okay?