While the initial public interest in Kim Dotcom's latest offering was so massive that the service rarely functioned, it seems that the craze has slowed down enough to offer some functionality. This is not to say there won't be any moments that the service hangs up or fails to respond, but the service is much more functional than it was at this time yesterday.
If the service still does not work for you, then simply give it a few more days. As the investments come rolling in along with paid clients, the service is likely to exponentially increase in power over the next month or so. Keep in mind also that this is an open beta, with forthcoming changes being mentioned on the mega sites blog.
Currently you are able to upload your content, and create a special link which you can share with your friends so they can download the content without an account on Mega. Currently there are no ads or wait times ( unless the service is swamped ) but no one knows how that may change in the future. Kim Dotcom is known for his aggressive advertising policies, so I would expect there to be some changes there in the coming months.
While it is uncertain just exactly how this service will shape up as compared to megaupload, it appears that Kim is taking the right steps to separate himself from the pirate image which brought the attention of government officials. The encryption system in place theoretically makes it impossible for even the company to know exactly what is stored, and there is already a page in place for people to report DMCA violations. The manner in which it is setup means that the responsibility is on you, the user, to not do anything illegal with the service.
Let me know what you think of the service.