Probably, by now, you'll have watched Episode of Merry unsubbed somewhere on the Internet; if you haven't, go watch it. Mainly told from Usopp's perspective while talking to Brook shortly before Film Z begins, it's mostly flashbacks to the Water 7 and Eneis Lobby arcs, although there are other bits near the start, such as when the crew first gets Merry, and getting to Skypiea. Unusually, most of the main fights are glossed over a lot, so if you're expecting to see a complete redraw of Luffy vs. Lucci... what we get is good, but it's not the whole fight, and there's going to be mixed opinions on whether it's as good as the original.
Perhaps of interest is that the dialogue isn't recycled - the actors have redone the lines for all the flashbacks, as well as them being redrawn. Most of the dialogue isn't quite the same as in the original, which can be slightly jarring if you're familiar with the original bits - Sogeking singing after sniping Spandam threw me completely because there was no backing music at the same time, and Robin's "I want to live!" just isn't the same. Generally, the new animations are well done, but the fights are cut down to the bare minimum needed - apart from the Lucci fight, all the Enies Lobby fights are the finishing moves and little else. Only one fight is shown in full detail, and that's Luffy vs. Usopp - makes sense, seeing as it's still Usopp's flashback in the first place.
Every time I watch Merry's funeral, I cry, and I suspect the same is true for you - this is more upsetting than Ace or Sabo's deaths by a long way. Frankly, I'm not proud of it, but I cannot help crying about a boat in an anime, and just when I thought I'd calmed down and the flashback had ended, the special hits you with one more thing that is, as far as I know, unseen so far. Unseen but probably predictable, but it still broke me and made me cry like staw: I'd be interested in hearing whether you too have emotions in the comments.