As a long-term player of spellcasters, I have a lot of different spellcards from different publishers, ranging from top-of-the-line commercial packs bought at my FLGS to PDFs bought here & elsewhere. The Spellcards 5e cards rank among my favourites, for being clear, concise, easy-to-use and attractive. My GM was so impressed he wants a set for himself!
The first thing to draw the eye is the legend in the top right, clearly showing at a glance whether the spell has verbal, somatic or material components, if it's a concentration spell (hugely important for 5e wizards!), and even if the material component is consumed. When your GM likes to throw adverse effects at you whilst you're spellcasting, and you have only seconds to pick a spell, the ability to spot one that can be used while restrained or silenced can be a lifesaver!
Highlighting ritual spells with another icon is another great idea, and I now game with a little stack of cards that I don't have to memorise but can cast with ten minutes' preparation (funny how the party's always willing to pause the dungeon crawl while I cast identify...).
Unlike almost every other spell card I've used, the cards don't slavishly copy the (sometimes tortured and convoluted) text of the PHb: instead, they're a clear summation of the rules, with nifty colour-coding for the results of failing & passing saves. Highlighting important words in the spell description (types of saves, durations, etc) means less time spent reading rules, fewer mistakes in the heat of battle, and more time crushing enemies!
Filling empty slots on pages with condition & area of effect rules cards as 'extras' is a wonderful idea, & it's great having these to hand as a quick reference during play. My only problem is that you then have to print multiples of these pages, scattered throughout the set, if you want to issue cards to several players affected by the same condition(s). Of course, by definition, using them as space-fillers means that's going to happen. The only suggestion I can make is that if Myth Merchant chooses to add separate pages to the PDF just for the condition/AoE rules, players & GMs will be very happy.
Lastly, kudos to Myth Merchant Press for continuing to support these cards, quickly correcting the (minor) errors & releasing improvements like variant card backs.
Pros: Clear & attractive art & icons; simple, easy-to-use rules; nice features like colour-coding; important rules are highlighted.
Cons: The PDF cards being laid out with a little white space between them is an annoying feature, as it means twice as many cuts.
Value for money (PDF): superb.
Rating: A solid 4/5, probably edging up to 4.5/5 if the cards were laid out as a single sheet & easier to cut! Overall, an impressive product.