There are a number of artistic reasons to shoot in black and white - it is still seen by some as photography in its purest form as it eliminates the distraction of color, letting the photographer focus on contrast, form, texture and composition. It can also create a mood and give a sense of timelessness to some photos. Whatever your reason, it is easy to take black and white photos with iPhone. You can put a lens filter on before taking the shot so you can see what it will look like, or you can apply it after. Here's how to do it on iPhone:
You won't find a "comic book" lens filter in the Camera app or even in the Photos app where you would expect it to be, but the filter does exist - buried in the Messages app. Why Apple hasn't just added the filter to Camera and Photos is anybody's guess, this way can be a royal pain if you want to take a lot of comic style photos not only because of the extra steps to get there, but because you have to apply the filter before taking the photo, you can't add it after like you can with the photos in the Photos app.
iPhone offers 9 filters that you can alter your photos with - Vivid, Vivid Warm, Vivid Cool, Dramatic, Dramatic Warm, Dramatic Cool, Mono, Silvertone and Noir. You can also tweak each one's intensity on a 0 to 100 scale, so you have quite a range of possibilities when you go to post-process your photos. While this may be enough for most people, if you are really into tweaking colors and textures in your photos, which is an art in itself, then the default array of filters probably seems a bit limited.
iOS allows you to assign names to people in your photos, which the app can then use to group all pictures of that person into one album. The Photos app even has a default People folder to hold all of your individual people albums. But what if you want to group all photos of an object into an album? Maybe you want an album of all of your photos of cars or dogs. You can actually do this quite easily in most cases, or at least get a good start on it.
You may have photos in your camera roll that you would rather others not see, because they are simply private - whether they are embarrassing, compromising, have private data like passwords in them or otherwise. You probably want to keep them out of sight of somebody who might be browsing your camera roll, whether it is someone who stole your phone or simply a friend you handed it to to check out some pics. iOS offers a way to hide photos but surprisingly doesn't let you put them in a password protected album.