LOOK OUT FOR THE ROFL FRAMES OF DOOM!
Here's my personal opinion:
The fall of reach - Hell yeah!
The flood - meh meh, William C. Dietz isn't as good as Eric Nylund if you ask me, and this is just ripping right from Halo 1.
First strike - Pretty cool, worth reading.
The ghost of Onyx - Pretty good, worth reading.
Contact harvest - complicated, pretty decent. I'd give it a shot
Cole protocol - I like. :P
On a side note:
Art books - awesome
All the comics - not so good
Other - mixed.