Played through Awakening last month and just started Echoes. Once I've finished Echoes I'll get on Three Houses; it'll be nice to have finally played through all the games in the series.
Awakening is pretty good but it really pales in comparison to Fates - the level design is too spotty for it to really be in the same realm of quality. The unit balance is a little awkward too (Robin is comically overpowered and makes Sigurd look balanced), but the real issue is just how simplistic a lot of the maps are. There's good stuff in there too, though; something like 60% of the maps are at least solid, and the game's fundamental mechanics are still enjoyable even if pairing up is generally less strategically interesting than rescuing. It's definitely better than the NES games and maybe better than Genealogy on the whole, but I think every other Fire Emblem is probably above it in quality - still enjoyed it though.
Only just started Echoes so I'm holding off on seriously judging it, but it really is a faithful remake of Gaiden, isn't it? The DS Fire Emblem games did a good job of translating the original games' level layouts, staying faithful to them while adding some great new twists and a lot of excellent mechanical refinements, but Echoes seems like it doesn't add much of interest at all to Gaiden - which has me worried because Gaiden is the worst game in the series by miles; the only one I don't think is at least pretty good. I've only just gotten through Act 1, but the start of the game is definitely weaker than Awakening's.
I think generally speaking, each generation of FE games (NES -> SNES -> GBA -> GC and Wii -> DS) is better than the one before it, with a handful of standout excellent games. Though Fates (Conquest) is one of the best games in the series, I'm not sure the same is true for the 3DS games.