I gave it a 3/5 for a numerous amount of reasons.
The Good - I-Street brings back the good old feel of I-Street and is something you can't miss. Mystic Timbers & KMAA are good examples of rides with good themes in the last few years. Rivertown is well-themed and really represents the backwoods feel. Coney Mall is in a sort of, "alright" situation. IMO, it feels like the color is just draining over the years. Flight of Fear is still themed to the point that it becomes alright.
The Eh - Planet Snoopy - I can't really say if it's bad or not because I don't go there too often, but from a general perspective it looks like your average Cedar Fair Snoopy area but with a little bit more theme added to it. Oktoberfest - I'm sequencing this so i'm running out of time, but Oktoberfest is themed well, but small area with a small amount attractions. So it gets an Eh.
The Bad - Action Zone. Not trying to be disrespectful but it feels like different colored legos sets being put with another set that doesn't match. Its just a bunch of coasters with different themes (most commonly horror/scary) slapped on a themed area. X-Base was alright, but with the removal of FH, I feel like the area is going to decrease and GP are going to miss it. Plus, the areas biggest theme is FOF, its only attraction. I feel like they could have done so much more for this area.
Soak City - While I wouldn't consider it an area, it feels like it. While I would put it in the "Eh", here's why. There is tropical themes in some places, but there are also places with less theme, the biggest plunge (see what I did there?) is the skyline/horizon. When you look in the distance, you'll either see woods or KI. It just throws it off the intended experience (Not the woods). I know KI can't do anything about it, but it just does (well, seeing the airtime hill on DB coming out of the treeline is pretty cool).
I ran out of time so if I missed anything, @ or quote me.