Feels bad to me really. I get the modal part allows you to shave on lands potentially and limit the potential of flood, but I feel the success of these cards will hinge on doing something at all stages of the game. The problem here is the spell is a bad top deck late, and the land side is probably not every useful late for any of them so you end up with a card that both sides wants to be played by turn 3.
So far the two we've seen feel super safe anyway, like could they have really not just made the discard side of this any nonland card. You are missing out on a lot with 3 and over, and the potential to whiff is much higher.
These spells are all really bad, but act as a land if you dont have any other.
You could put your deck full of these and not play any "real" lands, but then you end up with terrible spells AND terrible lands.
As of right now, the vast majority of these so far are just bad cards.
What makes them slightly better is the ability to BOUNCE the land back to your hand to get the spell effect later (even paying with the mana of the land itself a part of the cost).
So if we get some cards that bounce your own lands for free, that could be something to keep an eye on.
There's already Murasa Rootgrazer. EDIT: That's not true. I also don't think Valakut Awakening is bad. This one is less good, but VA is a rare and this is an uncommon. Since the lands are the same, one can only assume rarity will play a big part in the playability of the front. Awakening, however, seems great is most of the Counterburn decks I play on arena. Filtering any cards I don't currently need is great for those times where I draw 3 - 5 cards over a couple turns and end up with a hand full of basic lands. It also seems awesome with Teferi's Tutelage. Along with Channeled Force, you could almost start to make an Izzet Mill deck. Throw in Ruin Crab. Boom! Memes for days.