It's expensive, a lot (a LOT) of food whether you chose the menu or order à-la-carte (which I'd recommend), and not particularly light. It's a bit wild, especially the tasting menu, not always for the best.
I personally love it, but don't go there expecting every bite to blow you away, as some dishes seem to be about novelty just for the sake of it, and even the execution is not always fantastic. It may have looked very modern some time ago, but today I'd say it almost looks dated (I don't mind at all, just pointing that out). Still, the highs are very high.
Also, there is good wine to be had at very decent prices.
In fact I am currently considering going back there in a few weeks...
I've been to Gagnaire once (2 years ago).
It was one of the most fun I've had at a restaurant; service was exceptional, food great, wine not that expensive...
I was there in November and they had the "hunter's" menu (I did not do the tasting menu).
As I reported at the time, as much as it is "wild" it is very classical french cuisine.
As for suggestions, I'll leave that to others.