If you're planning on spending $150 at their participating partners (make sure you note it's not just $150 in spending anywhere) from February 14-17 anyway, then sure. Otherwise, not worth going out of your way and spending $150 for a return of $5 or so. I have a BMO Airmiles WE mastercard, but I won't be doing this. I've spent less than $150 for most shop the block promos and got 2000 AM (~$220)... now that's worth going out of your way for.
This is a mediocre promotion overall. The only one I see that I may do is the donate $5 and get 10 airmiles since helping homeless pets is a worthwhile cause.