Having flown on both the TU-154B/M and IL-62M aircraft, I can comment on the comfort, noise levels and what it's like to fly on both, but will focus on the TU-154.
Having engines mounted at the tail makes TU-154s quieter in the cabin than, say, the IL-86, with its loud, unhushed engines creating a roar aft of the wing which makes conversation difficult. Russian aircraft passenger seats are almost universally uncomfortable, having cushions which sag in the middle, and a metal bar across the rear third of the cushion which makes its presence known very well. However, on shorter legs, this is not too much of an issue. Besides the poor seat cushion design, economy-class seating pitch on most Russian-built Eastern European airliners is tight, to say the least. Being 5'8", I didn't have such an issue with the seating pitch on board TU-154s as would, say, someone of longer legs and greater height. Still, I felt it was a bit on the close side. Seats themselves are narrower than those in Western aircraft as well. One thing in particular - if you sit near a window exit, you may notice a chilly draft.
The seals around those aren't as tight as maybe they should be, allowing a bit of leakage. Overhead luggage space is very limited as well, with the B series having open racks, and the M series having enclosed bins the size of those on most smaller commuter aircraft. All TU-154s I flew in had overhead reading lights and vents, something not found on any Ilyushin (the vents are in the backs of the seats or facing bulkheads).
The TU-154 flies very smoothly in general, and rides out turbulence as well as any medium-haul Western aircraft I have flown on. The wings seem to flex a bit more as the ride gets bumpier, but I never experienced severe turbulence on board a TU-154. Landings are typically very smooth, as the undercarriage is beefier than what would typically be seen on a Western aircraft.
Overall, there is no reason to be worried about flying aboard a TU-154. If you are on an M series, production began in 1985, unless I am mistaken. Therefore, the aircraft are newer and more modern than their B series predecessors. B series tend to be a bit more rickety, unless the aircraft have recently been retrofitted with newer interiors, as have many of Aeroflot's and Pulkovo Airlines' TU-154B-2s.
Have a pleasant journey! I am sure we will all look forward to reading about it!