I'm actually using it myself currently. There are certainly rough edges (In fact, I think I'll be submitting a patch for boss_mail soon to tweak some of the default gen_smtp options that bit me). Migrations aren't as caliber or essential as in Rails, there is no asset pipeline, there isn't a scaffolding generator and so it must be filled manually, but it's still more-or-less a complete experience.
I don't know about "flexibility". It's much less rigid and opinionated than Rails, and it's easier to maintain modified versions of the source code in your project due to how Rebar handles dependencies. So I'd say it's pretty flexible.
Default library support, yes. But it's not that bad. Most major tasks are covered. The module system and resulting encapsulation (on top of runtime + OTP guarantees) means that using dumped libraries is easier and more reliable, so I had no qualms with reading and integrating, e.g. a wrapper to GraphicsMagick that serializes output to native Erlang proplists for batch image uploading.
The ETS session engine, the not strictly OO data mapper, functional tests, inbound mail server, in-memory MQ and model event watchers plus first-class WebSocket gen_servers are all nice perks.
My main concern is that commit activity has been dwindling down and the present lead maintainer (danikp, I think?) seems to be only sporadically active. But it can still be salvaged, I'd wager most of the serious users have private forks.
EDIT: By the way, out of curiosity, what "niches" are you using it for?
I don't know about "flexibility". It's much less rigid and opinionated than Rails, and it's easier to maintain modified versions of the source code in your project due to how Rebar handles dependencies. So I'd say it's pretty flexible.
Default library support, yes. But it's not that bad. Most major tasks are covered. The module system and resulting encapsulation (on top of runtime + OTP guarantees) means that using dumped libraries is easier and more reliable, so I had no qualms with reading and integrating, e.g. a wrapper to GraphicsMagick that serializes output to native Erlang proplists for batch image uploading.
The ETS session engine, the not strictly OO data mapper, functional tests, inbound mail server, in-memory MQ and model event watchers plus first-class WebSocket gen_servers are all nice perks.
My main concern is that commit activity has been dwindling down and the present lead maintainer (danikp, I think?) seems to be only sporadically active. But it can still be salvaged, I'd wager most of the serious users have private forks.
EDIT: By the way, out of curiosity, what "niches" are you using it for?