the clash is definitely a beginner board, very soft and forgiving, easy to learn on. it will be better than rental equipment for sure. a 2003 burton clash was my second board, i still have it, it has a few ptexed core shots but no blow outs and is still totally ride-able. it actually floats in pow pretty well and i expect the new one to be even better with the rocker, 1 inch setback and taper. it will ride kind of funny switch though and this messed me up, i hated riding switch on this board and never really learned.
that being said; depending on how often you ride and progress you will probably be ready to move up form it in at most 2 seasons, but more likely one.
The flow deck that Justin posted is a great deal
Decks that i would seriously look at are the K2-Raygun 159 or the Rome-Crail 158
Dude, suckin at somethin' is just the first step to bein' sorta good at somethin'