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It is wide enough for most things (20mm FF equiv), but pretty slow for the 35-50mm equiv. range (f3.4). So not exactly a great candidate to replace a few primes, and quite an odd range to replace a standard zoom... I would not be tempted as it misses the point.

I have such a point-missing lens too: 35-70mm f3.5-4.5. Misses the wide end to replace a standard zoom, and pretty slow to replace primes. But it cost me €8, which just makes it a fun thing to play with (and I happen to have a small 20mm prime to ease the wide angle pain).

In the scope of MFT, yes it's a great candidate to replace the primes in the overlapping range.
Plus, there is no prime < 12mm with such a fast aperture.

I have to opposite opinion about the focal range. For my type of photography, it's much more suitable than a classic (FF equiv) 24-70 range for example.
When I shoot landscape, 24mm is too limiting. When I mount a (FF quiv) 16-36mm zoom, I usually don't really need the extreme ultra-wide FL but I'm limited at the long end: 36mm is too short. I find the 20-50mm equiv range to be super useful and convenient. At 50mm you can still shoot nice portraits (my most used lens is the Fuji 35mm f1.4 lens which is about 52mm FF equiv).

As Klaus said, I think the main issue beside the price is the huge size.