There's a list of things that LVM does. One of its strongest is its ability to resize partitions easily. You can span multiple disks for one partition, etc.
Due to personal experience, and not from a weakness in LVM itself, I don't use it. I tried recovering data from my LVM drive, and had a hard time. I eventually got it off, but had to use some LVM tools to do it. Without LVM, you can plug your drive into your machine, and immediately have access to your data.
I suppose it's about what you want/need to do.