He's no Geddy Lee, but he's actually decent and can play some good bass lines. This is more evidenced in his older Snax stuff then it is with Linkin Park (where he's taken a far more simpler approach).
I really hope Phi on the next album and onwards really steps up his game in the bass department. He really doesn't play his potential. MTM was a step in the right direction, and an obvious improvement from Meteora as far as Bass playing goes, but when ATS dropped, little changed. And as good as ATS is, his basslines are nothing special. At the top of my head, his best work with LP are: Forgotten, Easier To Run, Wake, and In Pieces. All of which, he steps out of his comport zone and comes up with some interesting fills here and there. Granted, hes no John paul Jones, but hes a talented guy, that I hope on the next album, we hear more interesting stuff from him.
I like Dave's work in MTM a lot, but I agree with Derek, his playing is more recognizable in the Snax stuff than it is with LP.
he said himself on the Making of Meteora DVD he doesn't gravitate towards flashy bass playing but would rather just find creative ways to link what Brad's doing with the melody to what Rob's doing with the Rhythm.
Yeah but that was back in Meteora days, back when it was okay to create an album that sounded exactly what they did before. Now they're creating sounds that are unexpected and that challenge their musical abilities. He did flashy back in The Snax days, so I'm not sure why he changed his stance there. Dave has always seemed to be someone who was against the "12 song game" and making radio hits (as shown in the ATS DVD), so I'm surprised he hasn't shown his abilities off more on record.
Remove In Pieces from the list, and we'll be 100% on the same page. I'm still hoping he'll show his true skills on an LP song some day.
In response to the question in the original post, I can't think of any songs off the top of my head where he uses his fingers through the entire song. He tends to use a pick by default and switch to his fingers for quieter sections, particularly ones with long sustained notes.