Mega offers 50Gb of free file storage and is apparently/allegedly (I'm not going to pretend to be tech-savvy enough to authenticate the claim myself) protected end-to-end with 2048-bit RSA encryption. The idea being to create a storage service not nearly as vulnerable to what happened to its predecessor.
My first impression of Mega -- and I've read other similar impressions, so I assume it's not just me -- is that the service really isn't ready for prime time yet.
Part of that may be due to heavy launch-time demand straining its servers, etc., but I did have trouble signing up the first day (it just kept churning -- came back yesterday and things worked), and so far I've been able to successfully upload only one small file (208Kb), while my other upload attempt (6.4Mb) has been sitting in the queue for quite a while at 0% and with an estimated upload time of "infinity."
According to Mega's blog, it's probably not worth bothering with the service unless you're willing to use the Google Chrome browser. Which, of course, I do (in fact, I use the Chrome OS).
If it wasn't for the who and why of all this, I'd recommend writing Mega off -- at least for the moment -- and going with other existing options (Dropbox, Google Drive, Mediafire, etc.) that already work pretty well, and that will accommodate your primitive, buggy, virus-ridden, exploit-vulnerable, rub-two-sticks-together-and-hope-for-fire "browsers."
But the who and why are important. The US tried to shut down Dotcom for no better reason than that some large US business interests find the services he offers ... inconvenient. He was briefly held as a political prisoner in New Zealand under threat of extradition to a rogue nation (the United States) with a pretty nasty record of denying due process, disappearing (and sometimes just plain murdering) people, torturing prisoners, etc. (fortunately New Zealand, unlike the US, still has courts that sometimes abide by, you know, the law and stuff).
I want Kim Dotcom to succeed because all the usual suspects are trying to ensure that he fails. So I hope you'll give Mega a chance -- use it from the very start, and use it more as it proves itself. I suspect that the problems will be ironed out in short order, unless the US government launches an illegal cyber-war of aggression to try and take the site down ... and hopefully even in that case.