Criticism I've seen directed against Requiem from Masquerade-fans are:
Vampires seem kind of weak compared to mortals. It might have been a first edition Requiem thing, but it could also have been a general misinterpretation of the new iteration the Storyteller system. In nWoD, a single success is all you need, while oWoD regarded that as succeeding at a cost or just barely scraping by.
The setting felt under-developed and/or directionless nWoD adapted a toolbox approach to it's new line of games, that asked the GM to choose the parts they fancied, rather than read up on a pre-existing detailed setting. This could also have been a problem of communication, where players used ALL options provided, and felt it was both needlessly complex and lacking in substance.
Me myself was pretty disinterested in the nWoD stuff, except for Hunter: the Vigil. I had come into V:tM late (2003-ish) and had no interest in putting it down to play another vampire game that was "the same but different". I came around with the release of Blood and Smoke, which came to be rebranded into a stand-alone Requiem 2nd Edition. I think it's a superior game to V:tM - the mechanics are stream-lined and enforce the themes of personal horror.
But the setting is what you make of it, which is both a blessing and a curse. Having personally invested so much in Masquerade, I'd probably just recreate that with the tools and systems provided in Requiem. But with players completely new to WoD, I'd likely point them to nWoD games (2nd Ed, if available, that is!).