There's nothing wrong with the older TTR but a lot depends on how it's been treated before you got it.
Since the oil content is 1.1 litres and to skimp on oil changing is a bad policy.
To be on the safe side if I were you I'd change the oil AND filter on getting the bike, also check & clean the air filter, check the spark plug, check the tyres and their pressures, check the front & rear brake pads, check the lights and other electrical stuff.
I would advise you to read all the articles in The TTR250 FAQ web pages link at the top left side of this page - it's full of details and answers to help you.
Since yours may not have a kick starter then the electric starter has to be reliable. If there is a clunk noise when you switch the engiine off then be careful because that's the first sign the sprag is breaking up. I've only had my TTR about two years and I've had no bother (yet) with the starter so they are pretty reliable - BUT they are the weak bit of the TTR.
Overall the TTR is a very reliable and economical trail bike. I'm sure you'll get to know it very well and be pleased with it.
Where is the oil filter housing placed and is it easily accessible and whats the best oil for commuting is Comma Semi Synthetic Motorbike oil good as use that in the townmate and is good quality and reasonably.