1. Battery Life
That is the question eh? I dreamed up my own comparison - Metroid Prime Pinball in the DS slot and the rumble pack accessory in the GBA slot versus the G6 Lite in the GBA slot and a NoPass (SuperKey & Neo MK4 Mini currently) in the DS slot. It seems fair to me - why compare battery life of a NoPass & Flash Cart to just a commercial NDS cart? Doesn't make sense.
On my DS Lite (brightness level 3), Metroid Prime Pinball + Rumble Pack went from full charge to death in 10 hours, 37 minutes. SuperKey + G6 Lite went from full charge to death in 10 hours, 19 minutes. Neo MK4 Mini + G6 Lite went from full charge to death in 10 hours, 12 minutes. The G6 Lite with the NoPass removed after booting went from full charge to death in 10 hours, 48 minutes.
That's by no means a scientific test, I'd have to do it many more times to get a clear picture. I haven't had the cart all that long, so that's the best I can give you right now. Also, my DS Lite is still virtually new in terms of the charging cycle, so the battery hasn't lost any of it's 'chargability' yet.
So please, take my preliminary results with a grain of salt!
2. What don't I like?
That it only came in white after I saw how perfectly it matched up with the DS Lite. I've never cared much about the flash kit fitting flush, but once you actually see it in the DS..it's a thing of beauty. To have it match my DS would be icing on an already sweet cake.
I don't like how tightly the G6 Lite fits in the USB burner - it feels like I'm going to wreck it every time I pull it in and out, and let me tell you - over the past few days I've done it enough times that it should have loosened up by now if it was going to. This must be by design, and it's still disconcerting. I'm sure it won't ruin anything at this point, but it's a niggle for me. I like to treat my equipment well, and it just takes a little more effort than I'm comfortable with to pull it on/off.
I don't like the lack of documentation on certain features - for example when writing NDS roms, the choice between 'doFAT' & 'Normal', or when writing GBA roms, the choice between 'Hardware', 'Hardware+Software' or 'Software'. There is too much left for the user to discover, when a little bit of documentation could go a long way towards clearing some confusion.
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Other than that..so far it's been a really positive experience. The PC-side software is great, the menus on both the GBA & NDS loaders are great, the customization is easy, the compatibility (for me so far) is 100% with no effort or messing around with the patching settings. The Real Time Save support and Software Reset work with all the games I've tried. The speed, both transferring files to the cart and booting them is absolutely wonderful, and makes me stick all of my removable media solutions back in the drawer. The save management system is top-notch, having the saves automatically written directly to the card regardless of what you choose to play and not having to respond 'Ok' to any prompts (M3, I'm looking at you) is wonderful.
The cart is a real treat, and so far everything is as advertised. I'm currently writing up a review that will go into some more detail, but this was definitely a non-regretable purchase.