Generally very happy. Quality is good. Interface is fine. DVR service is key (but see below). The ability to watch wherever I am is really nice.
Two problems.
1 - The DVR service isn't all it seems to be. Generally it works really well. Much more responsive than a virtual DVR from a cable company, and there is no limit to how much you can save. One big problem, however, is that if a show you record is also available on demand, then you have to watch the on demand version, which means there are commercials you can't fast forward through. It doesn't apply to very many programs; sports are generally fine, but late night shows (Colbert, SNL, etc) will be chock full of commercials.
2 - There are a few minor holes in the lineup. No Viacom networks (Nick, MTV, Comedy Central), no PBS, no local stations outside of the networks (i.e. no Yankees on PIX 11), no Univision for soccer or MSG for those games. On the other hand, I do get the SEC Network and the Tennis Channel, which Optimum wouldn't provide.