I've been to SB 5 times now and waited to review until I've had multiple trips. I did this as I hold Meatheads in very high regard and didn't want to judge too early.
There is absolutely room in B/N for both Smash Burger and Meatheads. If you like the thin, match-stick style fries (think Steak N' Shake), Smash Burger is your place. My preference for fries is the thicker, steak fry style. Meatheads gets the edge in my book, but that's not to say Smash Burger's fries aren't good. Just a preference.
Service is friendly, and the burgers are fantastic. On occasion, the delivery time from order to table is a bit sluggish, but you can anticipate when that'll happen (empty tables + long line = lots of new tickets in the kitchen).
If anything, they should expand their dining room to accommodate rush times. Lots of corporate folks interpret their half hour lunch literally and would avoid SB because of it.
Overall SB is very good. I think Meatheads wins by a nose, but that doesn't mean I'll choose one over the other. I enjoy both.
Had the Windy City Chicken sandwich this time & previously had a burger. The sandwiches are oversalted and the chicken is only 1/4" - 3/8" thick or so but still $6.99 without fries. However, the Smash Fries were good and all beers (including Goose Island and Schafly's are $2.99 or $9.99 a bucket (4?).
Burgers are similar to Steak n Shake but SNS is better at a lower price.