Bad fielder, can't run, low OBP. Hits home runs.
Moss hit one HR per 16.57 plate appearances in 2016, and put up a .784 OPS overall. OBP of .300
Ryan Howard (!) hit one HR per 14.48 plate appearances in 2016, with a .710 OPS overall. OBP of .257
So, with Moss you get a somewhat better (but not good) OPS, and somewhat fewer HR per plate appearance than with Howard.
But...somehow, I don't think that "replacing Ryan Howard in the lineup," with a player who may be marginally better (or not, depending on what you think you need) is, or should be, a priority for the Phillies.
I suppose you could argue that Moss "plays" left field, whereas Howard cannot.
I think we can do better. It's not at all clear that just putting Darin Ruf in LF wouldn't be better than Moss (although he's right-handed) - and I'm no particular fan of Ruf at this stage in his career.