His 2013/14 season definitely does get looked upon in a harsher light than it should. He did have an extremely talented forward in Suarez leading the line, but it's worth noting Suarez really started to consistently score and hit his best form when Rodgers arrived. Whether that's coincidental or not is questionable, though. Irrespective of that though he still managed to get the best out of Sturridge, and had Sterling and Henderson playing some of their best football. Additionally, it was probably Gerrard's last good season for the club.
Obviously it's difficult to judge a manager on the SPL, but even if he's in an extremely easy job he's still done fantastically domestically; won every single game bar one, already got a domestic cup under his belt, and may win a domestic treble. That should be the expectations he's meeting this season but going unbeaten and winning a treble, all while playing good football, would be fantastic, and I'm not sure it's something that's been done before. Celtic won the treble in 00/01 and Rangers won it in 02/03 in recent times. Celtic won 23 or their first 24 games in 03/04 (drawing the opener) but had some slip-ups as the season went on and finished on 98 points. Right now you'd expect Rodgers to surpass that and break 100 points.
His problem, though, is obviously setting up a team defensively. He can produce good attacking football, but his teams concede at the back and can lack discipline. Celtic's away loss to Barca this season demonstrated that. They were going to lose either way, granted, but their defence genuinely looked awful at times and was utterly torn apart. Obviously he's not got that problem in the SPL though, because he can generally just attack and be guaranteed a win.
He's still young, too. 44-years old and has a lot of experience under his belt. You'd imagine he'll continue to learn as he develops. He's certainly much, much better than the SPL, and would make a solid manager for a mid-table side at the very least, and could possibly have another go at a big club.