i just succumbed and subscribed to tidal in order to compare it to spotify. results are mixed. tidal's sound quality is unarguably better (it's not a vhs-to-dvd improvement, but significant nonetheless) and i actually prefer its interface, which is simpler and more intuitive than spotify's, although as others have opined its search functions aren't as intelligent. tidal's library is, for my tastes, perfectly fine, about 85/% as good as spotify. however: (a) tidal's mobile platform is buggy and unreliable--lots of delays, buffers, etc.; (b) volume is significantly lower; probably a function of the flac format--i really need to crank up my phone; and (c) streaming tidal through my oppo bdp (one of its main attractions) requires use of an app on my mobile phone, which is cumbersome.
as a related aside, numerous pundits are predicting tidal's imminent demise, all citing the $20/mo. price as the weighing factor. this surprises the hell out of me--consumers don't seem to have a problem paying more than that for cable channels or sports packages + you can actually get the service for less if you prepay. there also appears to be artist backlash over the service being too "corporate," even though the same artists are getting higher royalties from tidal. others claim samsung is acquiring tidal, which sounds interesting.