Serotta's are nice bikes but they cost as much as the big boys like MOOTS, Colnago, Parlee and Time. Yet, serotta bikes cannot match the build quality, craftsmanship and racing geometry of these manufacturers. Compare a legend ti to a MOOTS Vamoots SL and you will see what I am talking about. The welds and build quality on a lengend ti look as if they were built by autistic workers when compared to the Moots frames. But the real test is in the ride quality. These other builders and others make frames that are fast, light, stiff, durable and yet vertically compliant. In contrast, the serotta frames that I have ridden are relatively heavy and flexy.
Serotta does make some very comfortable and plush bikes. If your riding style is more recreational and touring then serotta may be a good choice. But, if you are more of a crit or racer type then serotta isn't the best choice.
Another thing that bothers me about serotta is that they are really dishonest about the whole custom thing. Custom does have a place in cycling and there are certainly riders out there who can benefit from a custom geometry. But, with serotta you do not have a choice. You pay for custom regardless of whether you want it or not, and that's dishonest IMO. With top frame builders like MOOTS or Colnago and others, you pay an extra fee for custom. So, you have the choice of paying for custom or not. Also remember that custom frames are really just a bunch of tubes welded together. The geometry hasn't been optimized for anything - no wind tunnel testing, no stiffness testing, no aerodynamics design, no history of racing. And selling a custom frame would be nightmare since there aren't many guys out there who are willing to pay for a frame that was built for someone else.
If you are an old guy whose bones ache when bending over on a road bike and who is mostly a recreational rider and who doesn't race then serotta would be a good choice. Otherwise, you would be better off looking elsewhere.