While The Smiler certainly isn't the smoothest of coasters, and I find it can be a tad inconsistent in the smoothness department, I certainly wouldn't say it's unbearably rough by any means! I still love the attraction; it's currently still my #2 coaster at Alton Towers, my #4 in the UK and my #7 overall, so I definitely have a lot of love for the ride! The ride also holds a very special place in my heart, as watching it get built was the very thing that set me on the path of theme park enthusiasm in the first place! Also, as @AstroDan mentioned above, it was unrealistic to expect Mako or Icon levels of smoothness from a coaster that packs nearly 4,000ft of track into a space little bigger than that of the average Vekoma Boomerang. Smoothness was never really The Smiler's greatest strength to start with; that award would go to its insanity and out and out relentlessness! The ride never lets up from the second you crest the first lift hill to the second you hit the final brake run!