Is the Discover 0% for 18month Promo Worth Getting?

Considering getting discover for the promo. This can be worth the hassle if the 0% APR equates to a significant amount of interest. Whats the best way to do this? Ive mostly been in the chase ecosystem until now, and have never used an apr bonus before. How much credit limit should I expect? If it is likely to be over $20k, then 3.5% of difference in interest in some bond fund might make it worth it?