Late to the party here, but I've had all three types - manual, continuous-clean, and self-clean. Currently, both my daily-driver ovens are not self-cleaners ('56 GE in Ogden, '62 Flair in St-Lib) and honestly, it's not that bad to keep them clean. As has been mentioned here, I do try to not let soils build up and burn on. I have found that a wipe-down with a cloth moistened with water and ammonia will knock out grease before it builds up. Racks get a treatment with regular oven cleaner, then a scrub down with a steel-wool pad if needed. (Side rant - cleaning those oven racks is easy to deal with if you have a deep laundry or utility sink - most homes no longer have these alas...GRRR)
I also have to admit that I find the Flair oven is very easy to keep clean - I swear that oven was designed for someone on the not-to-tall side like me. The swing-up oven door is a boon! I've used wall ovens before - a 60s GE with a removable door and and 80s Hotpoint with a non-removable one. The latter was replaced by the GE Wonder Kitchen... LOL
I got to use a continuous-clean oven first - my folks bought a 1974 Baycrest (Canadian department store rebadged Westinghouse) with one. I actually read the user book and as John also said, it instructed the owner to wrap the removable drip plate at the bottom of the oven with heavy foil. I did and that oven stayed looking fine until it was off-loaded in 2006. Of course after I had moved out of my father's house in 1986, that range saw very little baking and roasting activity... LOL
First self-cleaner was a mid-70s Bélanger (a Canadian brand which I think at the time was made by Tappan). When the self-clean cycle was working, I was disappointed with how it did. Heavy, crusty stuff just baked on harder to the oven walls. This was replaced by a 1977 Beaumark (Canadian department store rebadged Hotpoint) and I found it much better. Perhaps this was because the timer on the range was shot, so self-clean ran for as long as you wanted and as long as you forgot about it... LOL The last self-cleaner I had was a 2001 Whirlpool Gold - I was a little leery of it, as it was the model with the concealed bake element, but it did a decent job of self-cleaning. This had been the range in our old apartment in Montreal so it didn't see tons of baking and roasting though.
At the country houses, we had a succession of ranges... When I decided to "go turquoise", both ranges I had were non-self cleaners, but I survived!!
Just one last cleaning tip, I read in an old 'household hints' book to leave a dish of ammonia in a dirty oven overnight to loosen grease. It works reasonably well, I was afraid of the ammonia stinking up the house, but it really didn't!
