There's just not much that the VC forum offers that isn't satisfied over here. Most of the participants there are already here.

f32.net has a bit of a different crowd, being UK based. There are a few people who are more active there than here or APUG, so it's worth checking out. Barbara Lowry from Cooke Optics usually monitors that forum. More of the activity over there is in the photo critique section, which I don't follow too closely, but they do have a Travelling (UK spelling) Exhibition, like the APUG Traveling (US spelling) Portfolio, but it's in a tube to accommodate bigger prints, and has more digital output, which one doesn't see as much of in the APUG portfolio (occasionally, though).