I moved to a 3 bed house in Leyton 5 years ago after renting a place in Fulham. It was certainly rough around the edges then with absolutely no pubs/shops worth going to at all - At a stretch there was the Birkbeck tavern. The attraction was that you could buy a 3 bed house for under 250k, bang on the central line and the prospect of the Olympic park being built.
The biggest change has been the Olympic park which is amazing. There are fantastic playgrounds, Westfield shopping centre, the velodrome, pool and masses of open space. Stratford international can get you into King Cross in under 10 mins! There are masses of flats being built and a whole new community but my only concern is that they lack design flair and look identical to 1960s tower blocks and will age quickly. Leyton does not need to worry with its pretty victorian terraces!
Over time, Leyton has changed with new surprises popping up all the time. The Leyton Technical, Petite robe rose, drapers field park, olympic park to name a few. Oh and make a trip for breakfast at Mrs G's kitchen on Langthorne Road - the food and service is amazing!
The council have also done a really great job of revamping the high street shop fronts and has been featured in many articles on regeneration - what a difference putting the metal shutters on the inside makes. Alas the shops themselves have not changed much - Chicken shops, betting shops and other tat.
In my opinion the best roads are the ones south of the station. They are only 5 min walk to the central line and very close to the Olympic park, Westfield and Stratford international. You can even walk to some of the places in Hackney Wick (Counter cafe & Crate).
The area still has a way to go but is going in the right direction, so any purchase would be a wise mid/long term investment in my opinion. It is still rough around the edges, still has people chiselling off original stonework to make way for hideous double glazed front porches, still has landlords cramming as many people into illegal extensions as possible and still has people fly tipping in the street.
Having said that. prices have more than doubled in the past 4-5 years. People buying in the area are mainly the ones cashing in on expensive 2 bed flats in Hackney/Stoke Newington and want a 3 bed house within proximity of the east end vibe. The 'Leyton Village' twitter feed is blasting out propaganda about anything to do with 'gentrification' in Leyton and is a catalyst for change.
As far as schools go, they do have a very high %age of children with English as an additional language and %age on free school meals, this reflects the demographic. The teaching standards in some schools are very high.
All in all, I would recommend the place (if you want to stay in London) as both an investment and place to live where you get a whole lot more for your money in a well connected area that is moving slowly in the right direction.