If it's crap ... We'll tell you
Serious Co-Host?!?! Welcome to your opinion of course, but that was prehaps one of the WOOOORRRRST finales i have ever seen in my life. Not even the BSG finale had me this disappointed, and i like far more of that show than Smallville.
And LOST finale rocked, and definitely in Comparison to Smallville. Characters were consistant and got a satisfying conclusion, nothing was just a rehash of what was shown before, and as for mysterious -MOST were answered or hinted at throughout the entire series, and the epilogue answered a few more. Also they could never just tell you the answer because doing so would drastically lower the mystery of the show.
Smallville on the other hand wasted the first blo*dy hour rehashing EVERYTHING they had done in the last three Season with Clark doubting himself and the different sides of his life, having ANOTHER talk to mum, dad and friends about it, useless relationship drama with Lois that had been dealt with completely over last few seasons, the ultimate evil defeated in a second, same for his trio, and apocalypse just pushed away like nothing. Welling wasn't even in the suit properly and Lex return may as well been the clone from start of the season!!!
OH and my big one- Lex Luthor's development over 10 fu*king years WASTED!!! A great final scene between him and clark useless because it basically doesnt happen now and no explanation why Luthor would still be evil. As you yourself said Co-Host "why not say this is a different universe", WHY NOT have Lex just know Superman's identity. Hell the convo between them showed he was concerned with Beating Superman, not Clark. AND it doesnt answer how hundreds of villains know Clark's identity anyway! I would have accepted it if Lex somehow managed to retain his negative memories and hatred for clark (like how memories developed in clone) but NOPE all undone.