Great fun, but no GTA4
.It does what GTA4 didn't: It had the fun, planes, tanks(somewhat), wacky side missions, more color, unrealistic fun.
.The story wasn't so great, it was a run along story. But I found myself wandering off, getting more and more into the game's minuscule story. After awhile the activities became the story for me after awhile, wanting to dominate and wipe a gang out, as if I wanted this stuff for my self.
.Physics weren't to tight, but fun to play around with.
.The silly weapon choice was great.
.Online wasn't so great, GTA4 gave you a whole city to play around with online, Saints Row confined you to small maps, and not as many modes as GTA4.
For me there is a time for fun in video games, and a time for seriousness, and I like both. Saints Row 2 provided a whole lot of fun. If you are a gamer looking for a fun and non confined sandbox games(Assassins Creed) you might want to check this out.
But I rather have my fun and seriousness counterbalanced.