This didn't start well, with 1A: Popular web portal (MSN) (I give it a D+ for abbreviation and brand name), nor did 1D: Does course work? (MOWS) work for me all that well - I assume it's referring to a golf course. But enough carping. Let's get to the good stuff!
The puzzle definitely played hard overall, which is a nice change for a Sunday. And the reason is all of those triple-checked letters (the ones in the circles). See, they have to work in the standard across and down answers, but also in the diagonal theme answers. You'll notice that around these squares are a lot of consecutive vowels or consecutive consonants (c.f. USFL, FUEL, IDAHOES).
I really enjoyed the theme, though. First of all, who doesn't like Robert Frost? THEROADNOTTAKEN is almost certainly his most well-known poem, but I myself am particular fond of "Design," as well as "Mending Wall." Nonetheless, here we get a choice of diverging theme answers. Humorously, the road not taken here is THEROADTOHELL. Or I hope that's the one I didn't take.
In the four other theme answers, the initial word has a new definition in the divergent answer. I think I liked DRAGANDDROP vs DRAGSHOW best. In WAYNESWORLD and PATHFINDERS, the alternate answers actually change the entire word, which doesn't seem as clever. And DRIVEINARUN vs DRIVERSED, the initial words are too similar. Still, I liked the clue for 97A: Bring someone home ... I did not parse that correctly until I had the entire answer in place.
There was a minitheme about divinity, with GODHELPUS, LAWD, and YAHWEH. What do people think about "Lawd?" Is that okay? Seems like a stretch, and while I liked JAWA and JAFAR, perhaps "lewd" with "ewer" or some such mixture would have been preferable.
Why was 82A: Heads overseas? (WCS) a challenge? I was stuck thinking of actual heads, with "têtes" coming to mind immediately. Then my brain couldn't get out of that rut. The other answer I had a hard time with was 11A: Braggadocio (BIGTALK). I had BI_TAL_, and neither GIA Carangi nor the KARA Sea were known to me. Fortunately I was solving in the car with Hope, and she suggested it might start with "big". Good save!
It only remains for me to mention good answers NOYOUDIDNT, THEBEEGEES, and BELOWZERO, and this review is finished. The SOONER the better, no?