ive got one and i love it it only decreses battery quikly if u have it on its highest light setting which i dont and it battery lasts about 5-7 hours i like it much better than the dsl , i have never actually had a dsl my sisters got one as soon as they cam i out which was stupid as it was $200 and so i bought a preowned ds phat for $70 and i was happy so ive just jumped straight from ds phat to dsi here il make a table of what you shoud do
own:
No ds- Buy dsl
Ds Phat- Buy dsi
Dsl- Keep it until next upgrade
thats just my opinion and its kinda messed up lol so yeaaa... idk if it helps or not