He's a better keeper than Butland. Not sure that matters with managers generally showing a positive bias to players they sign and/or have worked with before but if it's a short term injury then hopefully can show he's better on the ball and similar in terms of shot stopping (Butland edges it) and dealing with crosses (Hennessey edges it).
Do we want him as Palace's number two though? Depending on who is looking for a keeper in January, falling to third choice and getting a loan away may be better option.