70HP would have been a very attractive HP for a basic, but with Kingdra's use of pluspowers, it's not a safe boundary.
Jirachi rivals this card with the ability to use special :metal to reach the HP boundary as well as a strong second attack. It also keeps your card secret for suprise tactics, but stops your next draw.
Sableye is another effective starter, as is call energy.
The easiest way to compare Farfetch'd and Jirachi is to think of Farfetch'd as saying "search for a trainer then draw a card". If your deck style needs trainers more and values that extra draw, perhaps. Rare candy is a good example, something like Kingdra could use Farfetch'd to pull great ball, luxury ball or rare candy to fit the last jigsaw piece with the other cards in your hand. With a 4 Kingdra, 4 Candy build, you could Go and Collect the candy, great ball -> horsea, luxury ball -> kingdra or a pluspower to get the setup. Is it worthwhile in the long run? Worth testing, but I'd hedge my bets with "no".
6.5/10 - Something to consider, but nothing special.