I've had a lot of experience from this and IMO it's brilliant. I only have positive experiences of it and consider it an absolute 'no brainer'. My thoughts...
1) I agree with the earlier point that you need to have 'radio-ready' tracks. But ultimately that's the kind of exposure most bands/arists are looking for so IMO you should be uploading tracks you believe are of a quality that can be broadcast locally and hopefully nationally.
2) I can only speak about the artists in my region but the feedback I get from other bands I talk with is always excellent. However, as with anything you have to hope that the music you're producing is enjoyed and selected by the BBC team in your area. If they like it they'll play it (Sat evening from 8pm). If they think you're really interesting then they'll forward your tracks to the team in London for R1/R2 consideration.
3) I DO NOT believe there are constraints over genre. I've tracked a huge number of bands who have gone through this process and have regularly heard indie, r&b, reggae, pop, metal, folk, rap etc. etc.
We uploaded tracks and got local BBC radio coverage and then after a while National airplay on BBCR1 and a summer slot on the BBC Introducing stage at Glastonbury. It's therefore been great for generating industry interest (although as with anything it's just a piece in the overall jigsaw and is by no means an instant guarantee of success). note that this process was over several years, its not an overnight thing.
However, like I said before IMO it's a nobrainer.
