"Popular" by itself seems to convey what you want. If you wanted to single it out for extra praise you'd usually add to that.
I'd rate Tom's "promising" as about as good as any.
"Well liked" may serve.
"Better than average" or "better than many" or even "better than most" all convey a sense of noticeable or notable but are clearly not what you'd use in a 'rave review' so may suit your need.
Maybe "aspiring", "trending"(yuk), "up & coming", writer or story 'to watch'.
FWIW I'd rate "middling" in the "damned with faint praise" category. I'd be disappointed to have that rating applied to anything of mine (whether deserved or not :- ).