While this is impressive compared to earlier systems, just citing the T1 & T2 values does not actually tell you much about the usability of the system as a qubi

While this is impressive compared to earlier systems, just citing the T1 & T2 values does not actually tell you much about the usability of the system as a qubit. What really counts is the number of operations you can realize within the coherence time of the qubit, and as far as I can see from the paper this seems to be around 5-10 (which is two to three orders of magnitude below what e.g superconducting qubits currently offer). Also, the next step would be to show two-qubit operations with the system, which is another challenge that isn't easy to overcome. So only after increasing the coherence time by another two to three orders of magnitude and realizing a robust coupling mechanism would it make sense to think about scaling the system and building an actual quantum computer with it. Still, semiconductor qubits offer several interesting possibilities as Silicon technology is something that is significantly more robust and scalable than e.g. superconducting circuit technology (currently at least).