We seriously considered an oval pool, for a while it was what we were getting. I knew I would be installing it, I did ALOT of research on installation and in the end came to the difficult decision that it was simply more than I could do and I don't regret that decision.
I'm a pretty handy guy and not afraid to tackle tough jobs but to me installing an oval was simply more work, and complexity, than I could handle, especially for a first pool install. That was the final decision on oval versus round, also, the local prices for pool installs are ridiculous.
I'm not saying it's impossible to do, but the volume of dirt to remove/add is significant and the wall bracing system looked challenging.
If your planning to do an oval install yourself there are lots of videos out there showing how to do it, additionally if you go to most major pool manufacturers you can download pool manuals (for initial research the model is irrelevant) and you can study what is involved with putting up an oval.
My personal recommendation: if you want an oval and if you can afford it - get a good pool installer, if you can't (and you want an oval) make sure you fully study the install process.