As I have a 2.0 litre V6, although it is possible to get the oil filter off via the wheel arch (fiddly and messy job), I prefer to drive it up my modified ramps, whip off the undertray and drain off that way. It makes the job much cleaner and easier. As said above, you get all the old out completely and can inspect other things whilst the undertray's off. I've just done the ATF and have replaced a couple of rusty mounting screws and waterproof greased all the fittings. Some folks have difficulty refitting the tray but I just pop the middle on some wooden supports and work my way from front to back, moving the "woods" as I go. If the fixings are looked after, it's a five minute job.
Mike