I bought a Bessler drum to do 5x7 negs with and I'm very happy with it. That said I've only developed 3 pictures but it could not be easier.

Make sure that the drum you buy has ridges in it, or removable ridges. Some drums are smooth inside and don't have anywhere to put the negatives. At least that's what I understand. The Bessler 11x14 drum is what I have, I think it can do two 8x10s.

Also make sure you get the cap on tight and put it on the floor or somewhere where it can't fall. The first time I used it I put it on top of the toilet (yup, that's my darkroom) and it fell and the chems spilled out and the film got exposed. Doh!