Great round, getting it to feed from a mag (and eject properly) can be tough. Less noise, fuss etc. than the 222 or 223 but if you like low priced factory/surplus go with the 223.
The 221 does best with 40-50 grain bullets (my experience).
Easy to make hits with and good performance on crows and groundhogs (only things I have used it on) out to about 250-300 yards.