I'd like to point out that all of these authors (excepting only HPL himself) are British. Others have pointed this out, but it bears repeating. Most of these stories are set in England, which produces a different interpretation on Innsmouth than American writers. I suspect that the British simply have a different way of viewing things.
Most of the writing was excellent, and the rest was at least innovative. "Deepnet" suggests that as far as Deep Ones taking over humanity, there is more than one way to skin a cat. "Dagon's Bell" by Lumley is one of the most Lovecraftian stories in this collection and "Beyond the Reef", while a little hard to follow, drew in many elements from Lovecraft's Massachusetts.
Some of the writing I found very difficult to appreciate; "Down to the Boots" and "Only the End of the World Again". Maybe the British write in a less concrete way than American authors, but I really had no idea what these stories were about - they seemed more like fragments. Maybe I'm too uncultured to appreciate writing like this, but I felt it brought down the quality of the collection.
There were also a number of stories that I wondered why they used the Innsmouth device. As far as I could tell, they would have been good stories on their own and then had the Innsmouth/Deep Ones jammed in. It makes a poor ad hoc plot device - why not just develop your own ideas? "Homecoming" was the absolute worst offender - it's about going home to Romania after the end of communism only to find nothing has changed. The only connection to Innsmouth was calling the secret police "Deep Ones". I suppose metaphorically it is how the non-collaborators of Innsmouth might feel about their icthyic oppressors, but it's a real stretch to say it belongs.
Well, the stories themselves have been well reviewed below, so I'll leave them alone. It's a decent collection of interesting writing, sometimes loosely connected to the Lovecraftian canon. My only concern is that many stories seem to have had the plot device forcibly inserted.