Hands down the best bang for the buck from the entire SR line (and I do own most of them: 505 & 505M, 605, 705, you name it). And yes, it's a killer bass: perfectly balanced, light, very fast & comfy neck, awesome versatile modern tone. Congratz on your new bass!
PS: BM stands for for "brown mahogany" - it's just a color code. The model is simply called 505. I'm pointing this out becaude you'll see a lot of those letters added to the bass tag on websites that sell musical instruments (depending on the finish), but it's essentially the same model with a diffeent type of coat on (or finish). In fact from 50X model up you get the same bass, in just slightly different versions (ex: the 605 has an ash body as opposed to mahogany; the rest is identical).