Just to hip this up even further: 3 is a fine little movie. The kid is a super genius, like ridiculously intelligent even for the Home Alone premise, but if you accept that, it's alright and fun and a good movie. At least it's a different family. I think it's pretty underrated.
Two is pretty bad. It's a full out, beat-by-beat retread of the first movie, except everything is a little lazier and makes a little less sense. Small example: at one point, Kevin is running away from the bad guys, down the streets of New York. He sees a cab and runs inside. Kevin says something to the effect of "thanks mister, it's scary out there" and the Cab Driver turns around and yells "IT AINT MUCH BETTER IN HERE KID!" and Kevin screams and runs away.
Like, what? Why would a Cab driver do that to a small, terrified child? Just the weirdest, most random scene. It's not terribly offensive or anything, just feels underwritten compared to the first one.
If you rewatch 1 and 2 close together, you see how badly 1 destroys 2. 3 kind of brings it all back. I guess 4 and 5 drive it off of a cliff, haven't seen them.
1 ------ 3 --2 -- haven't seen the rest.