I felt the romances didn't take advantage of the bonus of spanning multiple games particularly well.
p.s Ending complaints drowned everything else at time. That doesn't mean there weren't complaints about other stuff, i was deeply unhappy at the massive expansion of auto-dialogue and mediocre content for me2 cast but when there's a massive trainwreck you don't stop to make a complaint about the coffee you had on the journey.
I haven't played through any of the females romances in ME (running through a male Shep for the first time right now, starting with ME2) But I thought the continuation of Garrus from ME2 to ME3 was done well. Thought Kaiden was handled well between the three games. Thane and Jacob.....not handled well.
I think one of the reasons why there is more 'attachment' to Shepard than the Warden or Hawke is due to you playing as Shepard in three games. Spending that much time with an avatar, you're likey to attach to it more. (my thoughts on why although I loved my Wardens and Hawkes, I identify more with Shepard....plus the whole idea of being able to be a kick-butt female in a stereotypical 'male' world (i.e. sci-fi and guns))
Of the DA romances I think I liked Zevran the best (also liked Morrigan...but I only romanced her 1x), mainly since it was more involved to get to the 'love' stage with him.....RL I'm okay with the transition from FwB to 'one and only'. Found Leliana to be all sorts of creepy wouldn't touch her again even with a 20 light-year pole. Romanced her one time. Alistair, I also liked, especially the first time playing as an elf and getting the 'I'm breaking up with becuase...king.' Where is Mel Brooks when you need him (although with the 'hardening' you can be your own Mel Brooks I guess)? Also liked the Anders (even when I knifed him) and Fenris romances in DA2 mainly since some of those romantic lines they said sound like stuff my husband would say....(he's so adorably cheesy at times). Romanced Merril once (too wide eye'd stupid for my taste), Isabella not at all.
Just got done with ME3. While initially my biggest complaint with ME3 was the ending....there is soooooooo much more to complain about....the amont of autodialogue (I mean heck, I VACUUMED my house yesterday while auto dialogue played), the inability to skip cut scenes (I've mixed up batches of cookies during these), the graphics issues (getting stuck on things....especially during the planet scanning and in the cockpit, then having to reload....ME2 is bad with this too...never had as many graphical 'sticks' in the DA games).....story stuff (ugh.....Quarians).