I’m probably about half way through now. Completely rinsed worlds 1 and 2, got through most of 3 - just boss + bonus level to go. I’ve not done any of the warp levels yet. About 150 bots collected.
I keep playing a level and thinking - this is awesome, this is the best one yet, then then I get to another and another. The quality hasn’t let up at all.
The collecting of the bots and then the little items for them is done with some much care and love. Every time I finish a level I’m off to the gatcha machine and then off round to see which bots I just collected new stuff for.
In terms of trickiness the main levels are really well checkpointed, I never felt held up paticularly by a tricky mob or section. The symbols levels are another matter, but they are there as a test of skills (and patience!). Done the triangle and circle sets so far. The circle ones - which unlocked after the triangle set - were a fair bit easier for me.
One final thing that is really nicely done. The end of each “world” isn’t a boss level - it’s a special specific game themed level. This acts not just as a reward for beating the boss, but a great way to finish off a world before moving on to the next one.