I'm going to go with everyone else here - if you've never heard anything from L7, then this is a decent place to start, something that will give you a general idea of what they sound like. But a 'best of'? Hardly.
This CD only covers 3 albums done by L7, the 3 they recorded when they were with Slash Records (as the name suggests). It includes some good stuff - "Mr. Integrity", "Bad Things", "Everglade", "Pretend We're Dead", etc. But it's nowhere near the best of just those three albums.
It misses out on a lot of other righteous songs, such as "Wargasm", "Slide", "This Ain't Pleasure", "Drama", "Shirley", and quite a few others.
Get this album only if you've never heard L7 before (punk / grunge / rock / alternative... whatever you want to call it). If you like it, than at /least/ get Hungry for Stink, Bricks Are Heavy, and The Beauty Process: Triple Platinum - those are the three albums represented by this 'best of' collection. Then you can check out the rest of L7. Just be prepared to blow your speakers out, and to have your mind blown.