PROS
- Puts paid to no-deal danger for a long time
- Allows for A50 revocation (which transition would not)
- Gives measure of stability to businesses (but see CONS below)
- Gives time for a People's Vote
- Gives time for Brexit preparedness, including proper scrutiny of the necessary laws
- May allow criminal court cases against Leave to complete
- May enable EU to complete additional trade deals (and full benefits of Japan/Canada to kick in)
- Prolongs uncertainty (will we see variants of TM's deal again and again and again)
- Likely to bring a change of PM (if you think that's good, imagine a hard Brexiter in charge of negotiations!)
- May go beyond Speaker's term
- Doesn't actually resolve anything
- May further fan the rise of the far right
Overall, I think the prize of avoiding no-deal pips it, but it's neither straightforward nor clear cut.