Is Kassadin secretly strong?

I've recently decided to pick up Kassadin. Now I am not really a good player by any means. This IS Vs. people in the Gold 3 - plat 4 level, so that may factor in.

The first item I bought was Luden's Echo. Between my E with Luden's proc and level 1 ult (insanely cheap on first cast) I had really good waveclear. One of his most commonly bought items is RoA, but I felt that would be counter to a Luden's rush, which was to offset his horrible early damage. I basically rushed heavy AP while forgoing any tankiness or mana (yes mana) and used his ult insanely sparingly, never going over 2 stacks.

I played 6 games, winning 4 (all the games I won I carried) and losing 2. One loss was my first Kass game, and my second I tried AD Kass. It's a small sample size, but I went against several standard Kassadin matchups. I destroyed Lux, who I believe is countered by Kass. She abused me hard early, but post 6 and after an item couldn't do anything. Same for Zed and Viktor, who I believe are also weak to Kassadin. I had a game vs. Yasuo, which I roamed bot for free kill.

Overall, the less tanky build would be shut down in a very long game where they can build against him, but I had an easy time getting fed early and getting my team fed quick If avoidinga tanky or mana centered build. I noticed that I shined in Mid game, which Kassadin with the usual RoA rush does not.

Does anyone else play Kassadin and have any input? I'm aware that after this recent buff (addition of a small AP scaling on ult) he may not be the lowest win rate in the game anymore, but I really think a glass cannon Kassadin build is much better than what's being used. After a meta shift away from tankier champions, I believe he'll be even better.