I think it is worth it for the roughly $30 that it costs (shipping included) on most online stores (Amazon, Barnes & Noble, Walmart, Abe Books, etc.) I got it for under $30 on Amazon. For that price, it was worth it, though it should have had a large fold out map of the sword cost. I was disappointed with the large area map: content lost in the crease and text too small to read comfortably (I have good vision, do not need glasses, but still feel like I need to look at the map with a magnifying glass to avoid eye strain). The map in Dungeonology is much better than that in SCAG and Dungeonology is an activity book for kids. Thankfully, they made the map available as for free as a high-res image you can download (
http://media.wizards.com/2015/images/dnd/resources/Sword-Coast-Map_HighRes.jpg).
I quit playing D&D before the Forgotten Realms, so when I started again in 5e, the setting was all new to me. I run a homebrew campaign and skipped all the adventure paths until Curse of Straud. But I still enjoyed reading the fluff in SCAG and it does inspire content for my homebrew campaign. Nobody in my group has used any of the crunch in SCAG, so the crunch was the least useful thing for me, until recently.
But, now that I'm starting to DM Adventurer's League games for kids, SCAG is GREAT. I'm starting with
In Volo's Wake, since the bite-sized mini adventures are very kid friendly (i.e. 1 to 2 hours better fits younger kids' attention spans). The adventures are all set in the area detailed in SCAG, so it is very helpful to have it as a reference. Also, the kids love looking through the book at the table, and the character options in it are now relevant as I have lots of new players creating characters.
So, for me, SCAG is a nice book that gets a lot of hate from those already familiar with the Forgotten Realms, who were hoping for much more. But as a setting book for players and GMs for the part of the Forgotten Realms where all the Adventure Paths (except Curse of Straud) and Adventurer's League modules are take place, it is a nice addition, IMO.