As a Thanemancer who was very disappointed to my LI's treatment in vanilla ME3, Thane romance content was what I anticipated the most from this DLC. So, I will write my feedback from this perspective.
While I think the memorial service, the video messages and the "ghost" were mostly well done and even touching (I actually cried when playing the ghost scene), the problem is... I didn't actually get to spend time with my LI, or rekindle the romance. I hoped for more time with my love interest; not with his son, or his ghost, or the messages he tried to send Shepard. Seeing that content only made me sad, and when I watch the scenes that others got with their LIs, I feel left out. Though I enjoyed chatting and celebrating with my old squadmates and laughed at their jokes, I couldn't help feeling like something was missing. I couldn't help thinking: "This would be so much more fun if Thane was here!"
I have to wonder, why is Thane the only LI (along with Kelly Chambers) who cannot participate the party? Or, to elaborate, why couldn't this DLC possibly take place before the Citadel coup? I have heard it is so that we needn't replay the game from that early on. But, if having actual content with my LI meant I'd have to replay from there, I would happily do it. The others could play it later if they so wanted. So I really don't see a good reason for why this DLC couldn't at least include a possibility to have Thane alive at the party and deepen the relationship between him and Shepard, even if he died later in the game.
In my opinion, Citadel DLC only fixed one problem regarding Thane's romance arc in ME3, and that is the lack of acknowledgement of his death. I feel like the DLC only gave Thanemancers what should have been in the vanilla game at the very least, if he was going to have a mandatory death. For some people, this DLC gave the closure they were looking for, and I'm sincerely happy for them. But personally, I won't be able to play ME3 with my canon LI ever again. Even though the post-death content is now satisfying, the romance content while Thane is alive still feels immersion-breaking to me. Shepard still acts coldly towards Thane in the hospital, there is no date, no paramour achievement, and the death feels forced. What little romance there is would still leave a bad taste in my mouth every time I'd play it.
I'm sorry to say this, for I appreciate the effort put in the post-death content, but I'm disappointed. What I hoped for was a date with Thane and him being present at the party, and perhaps even an option to keep him alive through the game -- the option every other LI already has. I got nothing of that; I got sad scenes and bittersweet videos, more reminders that my LI dies every time no matter what choices I make. And that's why this DLC wasn't as enjoyable to me as it could have been if every romance was treated equally. I could try playing it with someone else as my LI, as I did with vanilla ME3, but it'll never be the same. I will always keep thinking, "Why couldn't I have a scene like this with Thane, an LI that what presented as a choice equal to Garrus and Jacob back in ME2?"