I got this same bike last August and I have nothing bad to say about it (the frame/fit/ride). Rides like a cadillac and once fit, the cockpit is very comfortable for me. I had problems with the Jett saddle. I purchased an Avatar, for the moment -it's ok - I'm still trying other saddles and am currently waiting for a SelleAnAtomica to arrive at the house.

Like you, I want to upgrade my wheelset because as Jo-n-NY says, upgrading the wheelset is the upgrade to make. Mine came with the Mavic Open Sport rims, 105 hubs, and 25c Roubaix Pro tires. For a more immediate upgrade, I bought 23c Mondo S Works tires and I like these better. The Roubaix tires I had were sorta like mules compared to the S Works - tires do make a difference. Then, I was debating on whether to buy a wheelset, or get them custom built. I decided I wanted to take on the task of building my own wheels because I like doing that sort of thing. My SO built me a trueing stand according to some specifications outlined in a wheelbuilding book I have. DebW of this forum who only lives an hour from me, graciously gave me a rear wheel wheelbuilding lesson in April. I've decided on a black wheelset; Velocity Aerohead for the front and Aerohead OC for the back. I'm still deciding on what hubs to buy, either Chris King, White Industries, or Zipp. I need to get moving on this as it's already July. I'm not that heavy - I'll do 20 spokes on front, 24 on back which is what I have now. I too thought I like radially spoked wheels but only for their look - I've heard folks say they give a harsher ride, others say that's a myth. I'd prefer now to stay a little traditional: with 20 front/24 back I'll do a 2-cross pattern. Still less spokes than some, but it'll allow me to build my own and replace spokes myself if needed. I don't need or want a really deep rim or flat bladed spokes as I have mostly hills and don't have flats of any significant length that I can roar across here.

As far as any other upgrades, as you know the Comp comes with 105 and so either you are fine with that or you needed to keep the price down. Now that you have the 105, it's more expensive to buy and replace to Ultegra if you wanted to ugrade components.