The WiFi thermometers are coming out of the woodwork! I think this is great. It will create competition and prices should start to come down soon! Loki sounds very similar to several others, but the black ball design is much more attractive than Tappecue or Fireboard. Tappecue and Fireboard certainly aren't going to win any style points. Tappecue looks like it came straight off the deck of the starship Enterprise (I mean the the original Captain Kirk Enterprise for you youngsters out there), and Fireboard looks a little 90s. Most serious BBQers are not going to choose a product based on looks. But the average consumer probably will. Prices generally seem to be around $200 for these products, so I would take a look and compare. I think what will end up separating these will end up being the quality of the probes, and possibly a well designed app. The Fireboard probes look like they have a nice heavy connection between the probe and the wire. The Loki probes also appear to have a reinforced connection.
Tappecue with 4 probes: $199
Fireboard with 2 probes: $189
Fireboard with 6 probes (2 ambient, 4 food): $259
Loki with 4 probes: $224 ($139 preorder)
Meater block with 4 probes: $199 ($184 preorder)
Keep in mind that Meater has no wires, including on the probes. It is unproven technology, so it is a risk. I believe the wireless probe design is patented, or someone else would have knocked this off a long time ago! The others are pretty similar in concept, and have wired probes. The quality of the components is what will separate them.
Any other similar products out there that I did not list?