I have to say this game is among most buggy software I have ever encountered, joined it while Steam sales were on and I regret doing so. Spiral knights reminds me of some other titles, which keeps me interested. Plus I met some OK people, so it gets more interesting to log in.
Anyway, I'm willing to let go some issues like the uber lag on some levels which has killed me a few dozen times in these few weeks (my broadband connection usually works OK, I'm Europe based); the fact that some of the incoming strikes hit me even though I at the time I'm well outside of the enemy's striking distance (I'm assuming this relates to lag); the fact there are hits that get displayed even though they haven't actually happened; enemies which from time to time get 3-5 times tougher from what you would expect on current depth (for instance, an Ironclaw Thwacker in a Tier 1 danger room which can easily stand 20 level 10 Vile striker hits, with two low sword damage bonuses; by no means am I an experienced player, but 90% of the time I am able to clear a Tier 1 danger room single-handedly without too much effort, it's just that randomly it gets exponentially more difficult).
What I'm NOT willing to let go is my Miracle Cloak health bonus. This is a 4 star currently level 7 item, which gives me one (1) additional health bar instead of 4, according to wiki page here http://wiki.spiralknights.com/Miracle_Cloak the amount which should be delivered at levels past level 5.
Also, my Dusker cap, which is a star 3 item currently at level 6 which should be giving me 3 extra health bars gives me one, yes you read that correctly ONE.
To further illustrate my point -> http://img847.imageshack.us/img847/1478/bug1a.jpg
Back at the arcade -> http://img200.imageshack.us/img200/6493/arcadet.jpg
Had I purchased any energy, I would feel like a moron right now.
It depends on what tier you are playing and what heat level your equipment is at.
http://wiki.spiralknights.com/Clockworks#Equipment_Reduction