Blitz is good for opening exploration and pattern recognition. Aside from those two things - in my opinion - it's just plain fun. It's not good for your game to play continuous blitz if you're serious about improvement though.
Absolutely correct Tal. But I only have time to play longer time controls on weekends. So during the week I play 5/0 which does help my game. Twenty four hours ago my blitz rating was below 400. Now it's around 520. Sure that's a low rating but it also shows improvment. Just my playing 5/0 games I am learning how to play the French Defense which I think is a good choice for beginners to start off with. I certainly would not choose the Sicilian because for that a player definitely needs to have a lot of experience. I also want to start learning the Ruy Lopez because I understand that the Ruy is an open field of tactical opportunities that will help train my visualization. I plan on practicing these two openings this weekend where I'll have time to play a lot of 30/0 games.
I'd recommend playing 1/0 instead of 5/0. The best way to improve in chess is to play chess, so a beginner who wants to improve should play as much as possible. In the time it takes to play one 5/0 game, you can play five 1/0 games, so the latter is clearly a better use of your time, and a more efficient way to improve.