Fancy stuff is what separates the best apps from the rest, but there is a line. Just because you have fancy stuff wont make your app good. Your first priority should always be the fundamental features of your app. Also, even if your app is great, don’t go overboard with fanciness.
There are a lot of apps around that look like their developers/designers have just cherry-picked from a lot of the top apps on the app store. They will take slide navigation, fancy animations, etc etc and just ram them all into one app forgetting what the real goal is.
For example, the slide navigation is great for menus, but there are apps I have seen where it has been put into a single section just for the sake of it. Generally this is only used for the primary navigation of an app, and not just in a sub section.
Another case I have seen is a weird mutation of paging, where instead of a simple slide between pages, a strange flip animation has been used, which is extremely confusing for the user.
Don’t overcomplicate things, sometimes simple is better.