Pretty good. Not as as good as Goku, Tenshinhan, Krillin, Piccolo, Roshi or even Namek Vegeta and Yamcha.
Goku has fought well with a power disadvantage (eg vs Vegeta), Krillin has against Goku, Piccolo and Tenshinhan are probably around Goku's combat skill level since they fought evenly with him in the Budokai, Yamcha put in decent showings against the saibaman and Kami. Vegeta can be an idiot but he managed to beat Zarbon (I'd say he's less skilled than Goku early in Z, considering Goku with x2KK managed to hit Vegeta and even on Namek Vegeta already had his habit of spamming weak ki attacks vs Recooome).
In terms of skill potential he could be very good. Obviously he improved in terms of skills in Super, but I don't know if he's yet caught up with Goku or Vegeta (since I don't watch Super and the writers of the Super anime can't write a good fight scene to save their life anyway)