My experience with Mega is limited only to Windows and Android clients. And the browser-based client.
The Android client works a lot like the Dropbox client for Android. It lets you navigate your files and folders and click on files to download them to your device. You can also upload from your device, or just get a link to share a file/folder with someone else. It has more features and options than that, but that covers probably 90+% of what you'd want to do with Mega on Android.
The Windows client runs quietly in the tray, automatically syncing as per your settings. You can set up multiple local directories to sync to your Mega account for a "selective sync" by linking your local directories to certain subdirectories in your Mega account. Or you can just link one local directory to the "root" of your Mega account for a full sync (like how Dropbox works with everything having to be in the Dropbox folder.) The client's UI also shows you recently changed/added files, how much of your 50GB you're using, gives you quick access to your local Mega folder or your account on the Mega website, shows syncing status, etc.
It also has some interesting looking features (which I've never used because I only just found out about them while checking out the client for this writeup) such as "Import Links" which allows you to paste in a Mega link (or several in batch) to add them to your Mega account. "Stream from Mega" allows you to choose a file on your Mega account (or a Mega link from someone else's account) and stream it. I'm assuming this is for videos and possibly audio, but it looks like it allows you to select which application to open the file(s) with so I guess anything that makes sense to do that with will work.
And one major nice thing about Mega over Dropbox is that Mega has end-to-end encryption, so they can't snoop on or leak your files like Dropbox can and has.
In fact, writing this up, I've practically convinced myself to switch over to Mega from Dropbox. Hmm...