I played both of those on 360 along with Burnout and Bulletstorm. I also have Burnout on Steam. I will comment on what I know...
Burnout Paradise - No longer supported for multiplayer by EA, so (as far as I know) there is no way to play online, but it does have local multiplayer (I think from looking at the menus). It is a great racing game though if you like arcade racing. Highly recommended. If you liked other Burnout games, you'll love this one.
Bulletstorm - Meh. More fun in coop, but like most FPS campaigns it gets very repetitive, but at this price I would recommend it.
Mercenaries 2 - I absolutely loved this game in coop on 360. Some hilarious cutscenes, and a decent story. It got me at least 60 hours of gameplay. I highly recommend it.
The Sabotuer - I never got around to finishing it, but it is pretty much Mafia 2 with an Irish accent (which gets pretty annoying and it's laughable how poorly done it is). It isn't a bad time gameplay wise though, and sabotaging things is pretty fun. It would probably be worth a play through, but I can't recommend it since I only played about 5-10 hours of it.
Mirror's Edge - I haven't played more than the demo, but I have been looking to pick it up for PC on the cheap. From what I understand, it is worth the money and it is a great time to play.
As far as the pack's value, if I hadn't already played all of them (3 of them to death) I would definitely pick it up for $10. Well worth it IMO. Lots of game time in this pack. Hopefully this helps some of you on the edge.
Regarding Burnout Paradise, I was able to login and play online. (Freeburn online). When it asks you to enter your login, you need to enter your EA account name (Which may be different from your email) It's the name on the top right in the Origin client. You can also join matches against other online people.
So it looks like you can still play Burnout on-line.
Also, to get to the on-line menu, you hit [ESC] and then F1 or F2 function key to get to the menu.
Hope that helps anyone.