hmm... With all those expectations, you'll likely be disappointed.

I'd say Mote was one of the best 10 sci-fi I've read and I've read a lot of 'em. heh.. Most important? hmm.. dunno.. As "one" of the best first contact novels perhaps but I don't see it better than all of them. Clarke's Childhood's End for example. I'd recommend Mote unconditionally to anyone interested in sci/fi. And all of those below as necessary reading to say you read sci-fi
Mote -niven
Fire Upon The Deep -vinge
Gateway -pohl
Pride of Chanur -cherryh
Ringworld -niven
Titan (John Varley)
Ender's Game -card
Startide Rising -brin
Dune -herbert
Foundation -asimov
Childhood's End -clarke
Armor (John Steakley)
The Forever War -haldeman
Neuromancer -gibson
The Diamond Age -stephenson
Timescape -benford
Stand on Zanzibar -bruner
The Left Hand of Darkness - Ursula K. Le Guin
some others.. (maybe another 10-15 of the classics, Dick, Bester, Aldiss, Blish (case of conscience), Harrison, Keyes, Cordwainer Smith, more Le Guin - lots of things I've read once and remember as great but don't have a desire to cycle back into my rereads like the above..) Vance, Wolfe and Moorcock too though they're better known for their fantasy I think.
I'd recommend those to anyone. I used to recommend most Heinlein to anyone but .. I dunno, some of them seem to have aged more than others and I wouldn't do it now without rereading them first myself and I haven't had a chance. I'd guess Moon is a Harsh Mistress is probably still "finest kind"..