A few things to say about this card.
Right now, its highlighted use is usually its first attack. Hammerhead OHKOs Tynamos and has forced Hydreigon to run less dark Deinos or none at all. It absolutely wrecks a field full of Eelektriks, so Eels variants need a substitute strategy to deal with Landorus. Another big use has been putting pressure on Darkrai/Sableye/Hamers decks by being able to attack for a single energy, thus forcing them to abandon a Hammer stalling strategy (eventually). It can pick up random KO's here and there but otherwise that has been its biggest impact. Putting 60 damage on the field for one energy (or 90 if they're weak) and benefiting from Max Potion is very nice. It has caused less Eelektrik to see play thus allowing Tornadus to see more play, so you'll probably see Tornadus based decks using these.
Its second attack is nice if you already run it, but it doesn't see much use. Doing 150 is good for OHKOing any Stage 2, and doing 70 is randomly good. Most other decks usually won't let Landorus get 3 energy on it so you'll need to energy switch into it.
All of this said, I do think this is a good card but its slightly overrated. I see it played in so much, but I don't really think its good unless you have problems with Eels or maybe some Stage 2 decks. However, Eels doesn't see nearly as much play anymore so you better be sure you need the support from Landorus for those times you do run into it. Added coverage on Sableye if you get caught in a Hammer lock or catching Stage 2 basics on the bench are too situational, yet still a nice bonus.
Retreat cost and weakness are also gripes.
8/10