I've found Congo to be a stage that changes a lot for ness depending on who the opponent is. It is good for ness against a fox or a falcon because of the slants in the middle - if ness goes to the center and spams up-air, it makes his position pretty strong. Not to mention that he doesn't have to worry about lasers as much. However, the corner platforms are pretty high, and ness can have trouble getting up there against a character like kirby. Those platforms are pretty big and are slanted which can mess up tech chases and throws up there. I still think dreamland is ness's best stage against all characters besides probably kirby, jigglypuff, and pikachu (with those being better on hyrule). Also, the middle platforms, while they are good, are really small and it's not difficult for characters to DI off of them.
I also think peach's is ness's worst stage. I'm not sure why people feel good playing him there. No platforms for techchases, no recovery options, no walls, no ledges, no sweetspots. All a pikachu/fox player has to do is camp on the moving platforms and ness is almost shut down.
Regarding recovery, I don't regard congo good for recovery because there are almost 0 lagless recovery options for him there. Not to mention that stage is not that big and most characters can just go out and edgeguard. There is also no opportunity for some reverse ledge DI. Ness can go under the stage and up-air but he has to be really close to do it and it is very risky. I feel safest recovering with ness when I am up high with platforms near me and solid walls/ground. Maybe some point I'll make some pictures with some tips on what ness's options are in different scenarios (left-side-hyrule, right-side hyrule, above dreamland, below dreamland, etc.) since your approach for recovery should be different for each scenario.
While the recovery in that video that Yobolight posted may not be the best recovery usage, if you watch the context right before it, mario jumps out and tries to intercept the recovery and then I used up-b to stop myself from falling. I maybe could have just dropped down and used dair or something. Recovering from the spot that I did is probably the best spot to recover in the game for ness since it gives him the most options. Delaying the up-b I'd say is a definite strategy but doing it that close to the stage definitely was definitely a risky move. If you are looking to improve your recovery with ness the first step should be getting good at down-b sweetspots and up-b sweetspots (but doing it soon after your second jump so you still have some horizontal movement to get back to the ledge) so you don't have to use up-b at all.