Everyone thought they were having great success with them, until all the news came out about the corrupted or just plain wrong calibration files came out. I was the one who started a UMIK thread here, HTS, and I think AVS. I was psyched about the mic and tried to really promote it.......because I thought I was having great success.
I have experienced zero hardware issues, however, I also have a Behringer ECM8000 from cross spectrum. Terrific mic, with excellent calibration files, but it needs phantom power to run and I've had problems getting my external soundcard to be recognized on my mac so I had been looking for a new option. Voila, the UMIK came out and everyone thought it was perfect.
More to the point, if you read through the miniDSP forum on their own website, it is well documented what the problems are/were. To sum it up, first batch mics were fine in terms of hardware, but their calibration files were off below about 1khz. Not very useful. The batch 2 mics had hardware and software issues. The batch 3 mics are shipping now and everything is supposedly fixed. So now I have two mics, that function fine, but have no cal file so everything below 1khz is suspect.
To be fair to miniDSP they had a return/repair/swap option for all batch 1 and 2 people. I chose not to take them up on the return, because there's nothing wrong with the mic itself. I chose not to swap because I have no idea what I'd be getting in return. So now I'm just going to send one or both of them to cross spectrum at some point, pay a little more to have cal files that are accurate down to 5hz and up to 25Khz and that are guaranteed to be accurate.
I hope the UMIK issues are worked out because then it will finally be the product we all hoped it would be, but my trust in them (as far as the UMIK goes) is low so I invested my money elsewhere and am getting my ECM a little easier to use. At this point it should be as plug and play as a UMIk and twice as accurate.