I just finished playing through Layton Vs. Wright, and enjoyed it for the most part. The unique twist on testimonies was neat, as was the medieval-fantasy setting and how Phoenix reacted to it. The graphics and music were wonderful, and it was cool having classic Phoenix Wright and Maya taking on new cases. I've never played any of the Layton series before, but I enjoyed the brain-teaser puzzles too; the investigation parts of AA games can be a little dry, so I think Layton's contribution of puzzles helped in that regard.
One thing I wasn't a fan of (end game spoilers)
...was how all the magic of the world turned out to be not really magic, but "advanced technology". It's funny, because it's usually the opposite situation that annoys people (explaining anything fantastic with "it was magic") but in this case, especially since this was a special crossover, I think letting magic be magic would have been better than such a far-fetched end-game reveal. [Also, it's not like Maya's a magical spirit medium or anything.]
On one hand, it let the people of the town be real, which is sort of neat (especially since they could show up in the DLC chapters), but since they freely break the 4th wall in those chapters anyways, it wasn't totally necessary either.
Besides that issue, the story was pretty fun. Plus, seeing Edgeworth at the end (and in the next-to-last DLC chapter) makes me forgive the twist because Edgeworth rocks.
I do hope they localize the newest one, because I'm all for a drastic change in setting/characters/gameplay. I remember the first time I played AA4 I was a little weirded out by it because the tone and setting was so different, but after playing AA5 I went back and played it again and enjoyed it a lot more.