Depends! If you plan on programming, absolutely. If you just want to play other people's games, then only time will tell what the library will look like. A lot of the games are simple, being made by individuals and hobbyists, but there are some real gems out there.

Is it diffcult to make your own games?

It took me about a month to learn on the DSiWare version. Once you learn, it becomes second nature and is a lot of fun, but the initial learning process can be difficult.

However, I wholeheartedly recommend buying this whether you can learn or not, as many great games are being created for it.