It's weird, I watched both of the Goosebumps movies when they came out, and I liked part two more than the first. However, upon revisiting them, it's the exact opposite. While the first movie is a perfectly-made kids' film, that I will enjoy every October, the second movie may never get a third watch.
Overall, _Goosebumps 2_ feels like a step down, but that's not to say there are no good moments: to begin, this one feels like it could actually be a Goosebumps book adapted for the big screen. Also, I like that it has moments with a genuine horror feel; really, any moments with Slappy feel like a horror movie - only for kids.
Aside from that, there's not much to talk about. The characters are boring and goofy. The first movie had lots of humor, but it was used as a way to flesh out the characters and keep the story moving. Hell, even minor characters from the first movie had great dialog and felt important to the plot.

Moving on.
This is barely a sequel. There is only a mention of what transpired in the first movie, and Jack Black doesn't show up until the end. Really, without Slappy, and the magic Goosebumps books, the movies are completely unrelated.
I mentioned this already, but it needs repeating: the characters are so one dimensional. And who are we following here? Sonny, and Sam? Or Sarah? There was too much drama that didn't directly tie into the greater story.
I'm just really blown away by how well made the first movie is, and by how badly the ball was dropped here.
Just go watch the first movie.