According to the specs, the 550's contrast ratio is 3M:1 and the 950's 5M:1. As I understand it, there is no strict industry standard for how these numbers are derived so when trying to compare between sets, they have little meaning - though you'd think that numbers given by the same manufacturer would have some merit relatively speaking. PQs on each are decent and I don't recall 1 being that different from the other (except for the glare problem of the 550 and I, admittedly subjectively, seem to think the blacks on the 950 are a little deeper). I am about 1-2 weeks away from having mine professionally calibrated.
The magic remote is included with the 950 along with the standard remote. I have a Philips Pronto TSU9200, so I don't use either one of the LG remotes.
Otherwise, the 950 has internet (but doesn't include Pandora - which is something I use a lot) and has the wireless dongle included with the set. But since a lot of (mine included) BluRay players have WiFi internet (mine includes Pandora, NetFlix, VUDU, etc), I really don't use the internet capabilities of the TV.
The 2 things that stand above the 550 to me are the TruBlack filter and the form factor of the set's design. It was a lot of $$$ to upgrade but I just couldn't live with the 550 due to the glaring reflectivity of the screen.