I'm happy with the TSP, both during accumulation phase and now during decumulation phase.
I decided to withdraw via the "equal monthly payments" option. I can change the dollar amount of the payments once a year. When life circumstances change, such as when one claims SS, the monthly withdrawal amount can be changed as desired.
My TSP is in "G Fund", a government bond fund which is guaranteed never to lose share price value. My equity index funds are all in my taxable accounts. To me, my monthly withdrawals from the TSP seem like the next best thing to having a second pension.
Access to the TSP and G Fund is part of the agreed-upon benefits of federal employment, and those who would like this benefit enough to take the bad with the good can look through the many federal jobs available at USAJOBS - The Federal Government's Official Jobs Site
). It doesn't take long to get vested in the TSP (maybe 3 years? I have forgotten and I am hazy on all these details that don't apply to me), and if my recollection is correct you can roll over other 401K's to the TSP. Details and publications with the real information are available at http://www.tsp.gov