Since 2017 we’ve owned a 2006 LL Bean (with H6) with 91Kmi. that my parent’s bought new. I feel it’s basically a good car and family members who live in ME own several 4cyl. Subaru’s of that general vintage with 160kmi to over 250kmi with no serious issues (though a friend’s 2006 H4 OB needed head gaskets at ~ 90Kmi). At the mileage you’re considering much will depend upon the use and care it’s received.
Things we like: engine power - gobbs of it, at 95mph up hill in hot desert pushing a roof top box there’s still passing reserve. Transmission, and AWD in Sierra winters (with the right tires) work well. Love the ground clearance. Brakes are great. Handling is good (Pirelli All Season tires were fine on snow and ice and the present Michelins are even better, the Maine contingent likes Continentals). A/C is strong, even at 108degrees in desert. It’s comfortable on trips and pretty quiet, the sun roof is nice (be sure all 4 drains flow freely, the rear drains are hidden behind the wrap around bumper). Despite what some say spark plugs are relatively easy to change, following on-line instructions. Same for full ATF flushes, lines are easy to reach. The engine seems to do as well on Subaru’s conventional oil as it does on Subaru’s and several other brands of synthetics. Suggest changing <=5,000mi. (judging from continuous, summer interstate driving, any type oil) or 6mo., whichever is sooner - the owner’s. manual seems too long even for synthetics.
Not as great: Gas mileage - ~ 24-25mpg (premium) on interstates once the oil is warmed up and with very smooth transitions isn’t too bad, but going ~ 20-25mi. per trip on freeway gives ~ 20mpg, and mileage drops to 15-16mpg around town when driving 5-8mi. at a time. The front struts were bad at 47kmi and bushings had collapsed (they were 11yrs old) - there are better after-market struts. A front CV boot split at ~ 60kmi (the joint was good, so repaired with a $25 NAPA boot kit).
Catalytic converter heat shields are rattle prone - very expensive at the dealer but there are home brew ways to clamp them.
Subaru AWD especially doesn’t like mismatched tires (wears out the mechanism), check that all tires are the same model, size, and very close to the same wear. Tires should be within about 0.25inches (6mm) of each other in circumference (I measure with a flat tape), and rotated at the specified interval.
There are some complaints on the forums about valve cover gasket oil leaks and ours may be starting, but much less expensive than head gasket repair. Inspect for both head and valve cover leaks.
The auto cabin temp controls are a pain, set 1 degree higher or lower than the present temperature and they blast full hot or cold until the new set point is reached. We live with it.
The cabin air filter requires perhaps 40 minutes and many screws to change, but easier the second time. Ours is loaded up by 20,000mi.
Head light bulb changing (halogens) is a moderate pain, but doable. Illumination is good.
The FM radio range is much weaker than our other cars, but this might be just ours.
Check out the forum subaruoutback.org