I have not finished the game yet, I am about 20 hours in and on chapter 4. However, for a first impression I can say I'm genuinely enjoying it with a few caveats.
The game as far as I can tell is not as short as many are claiming. Everything I've experienced seems to point to this game being the same size/length as previous installments. It still has numerous side quests, granted they are as simple as they've always been. There are also all the same large Beasts and various side activities you find in the various zones, much like Alicization Lycoris. There are a few new side activities that will not spoil.
On next gen, the graphics, while not a huge upgrade, are definitely more crispt and vibrant and the inclusion of 60 FPS is a godsend.
The story has been good so far, though some of the dialogue (written) is not the best. Not horrible, but noticebly "meh". This is typically more evident in side quests.
Where Lycoris had a horrendously slow start, Last Recollection thrusts you right into the story and wastes no time getting the ball rolling. While you start at level 1, stats and damage numbers are much higher than in a traditional RPG to compensate for the fact that Kirito and everyone else has already been in Underworld for quite some time. The game makes you feel like you're an experienced swordsmen while still retaining the traditional leveling up process. HP starts at around 40,000 for party members and damage numbers are in the thousands to tens of thousands.
All weapons and weapon abilities are unlocked from the start, relegating the Skill Tree to combat abilities, secret techniques and various improvements to abilities you already have. There are other various gameplay features you will unlock along the way that I will not spoil.
Combat in general has been simplified while still retaining much of the depth from previous games. You now have Finisher abilities you can set; You can set up to 3, and these are abilities that will auto combo at the end of mashing square on PS and X on Xbox. You still have an ability wheel you can setup however you wish, and many abilities still have the capability of branching with precise timing. Weapon proficiency has been removed entirely.
Social aspects of the game have been toned down. You will still see characters in hubtowns, however there is little to no interactions with them. You will have various quest pop-ups around the map indicating a new personal conversation with various characters, however it is much lighter than in previous games. Bed scenes are still in the game, along with affection ratings for characters. As far as I can tell, raising affection/relationships is relegated to using a character in combat.
A noticable improvement in Last Recollection is the music. Boss fights and various big enemies have orchestral style music with choirs going off. It lends an "epic" feel to the bigger fights and I genuinely enjoyed this. Overworld noncombat music is also genuinely well done and enjoyable.
Lastly, upon entering chapter 3, character customization, multiplayer and other hubtown/social aspects become available.
All in all, it feels and plays like an upgraded Alicization Lycoris albeit with a few changes here and there. The performance and state of the game is much better than Lycoris at launch. If you enjoyed Lycoris or previous SAO games, you will likely enjoy Last Recollection.